- Photooxidation of n-heptanal in air: Norrish type I and II processes and quantum yield total pressure dependency
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Dilute mixtures of n-heptanal in synthetic air (up to 100 ppm) were photolyzed with fluorescent UV lamps (275-380 nm) at 298 K. The main photooxidation products, identified and quantitatively analyzed by FTIR spectroscopy, were pent-1-ene, CO, vinyl alcoh
- Tadic, Jovan M.,Juranic, Ivan O.,Moortgat, Geert K.
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- High yields of piperylene in the transfer dehydrogenation of pentane catalyzed by pincer-ligated iridium complexes
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Conjugated dienes are desirable reagents for several important applications. We report that sterically uncrowded PCP-pincer iridium complexes, including precursors of (iPr4PCP)Ir and (Me2tBu2PCP)Ir, catalyze the transfer d
- Kumar, Akshai,Hackenberg, Jason D.,Zhuo, Gao,Steffens, Andrew M.,Mironov, Oleg,Saxton, Robert J.,Goldman, Alan S.
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- Synthesis and catalytic investigation of organophilic Pd/graphite oxide nanocomposites
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Low-loaded, organophilic Pd/graphite oxide (Pd/GO) nanocomposites were synthesized from different Pd complex precursors by applying graphite oxide as a host material and tetradecyltrimethylammonium bromide (C14TAB) as a stabilizer. Structural investigation of the Pd/GO samples was performed by ICP-AES, XRD, N2 sorption and TEM measurements. It was found that monodispersed Pd nanoparticles were formed, ranging in size between 1 and 6 nm, both on the external surface and in the interlamellar space of GO. The samples proved to be highly active and selective catalysts for liquid-phase alkyne hydrogenations. The variation in the catalytic performances was attributed to the difference in the amount of interlamellar Pd particles, which participated in the reactions as active sites.
- Mastalir,Szabó,Király,Dékány
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- Hg(63P1) Photosensitization of Cyclohexanone. Role of Triplet Biradical Intermediates
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Hg(63P1) photosensitization of cyclohexanone results in the formation of pent-l-ene, cyclopentane and hex-5-enal, just as observed in the direct photolysis.As the pressure of added SF6 or Ar bath gas is increased, both the total product quantum yield and that of the hydrocarbon products decrease, while that of hex-5-enal increases.A comprehensive mechanism, differing in detail from those previously proposed, is now formulated to account quantitatively for the experimental observations.Two sequentially formed, energy randomized, vibrationally excited triplet biradicals are believed to be the important intermediates that lead to product formation.Thus α-C-C bond cleavage of triplet cyclohexanone yields an acyl-alkyl biradical. 3B*, that can give rise to both hex-5-enal and also, by loss of CO, to the penta-l.5-diyl biradical, 3PD*, the precursor of the hydrocarbon products.Rate constants for intersystem crossing of the two biradicals are deduced along with that for the fragmentation of 3B*.An RRKM treatment of this decomposition suggests that the observed rate constant is best fitted using a biradical excitation energy calculated by assuming a heat of formation for 3B greater than the value computed by conventional methods, which neglect electronic interaction.In addition, relative rate constants are obtained for the intramolecular disproportionation and cyclisation of 1B and 1PD when both vibrationally excited and thermalized.It is concluded that the critical energy for ring closure of 1PD is greater than that for isomerization to pent-l-ene.
- Baulch, D. L.,Lenney, Colburn P. W.,Montague, D. C.
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- A Mechanistic Study of the Rhodium-Catalyzed Cyclization of 4-Hexenals. Reactions of Deuterio-4-hexenals
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In independent experiments, four carbons in the 4-pentenal skeleton have been labeled with deuterium or methyl and the fate of each label has been determined as the pentenal was transformed into a cyclopentanone derivative by RhCl(PPh3)3 (1) at 24-26 deg C.The catalyst converted 4-hexenal to 2-methylcyclopentanone (2) in CHCl3 and C6H6.Approximately equivalent amounts of hydrocarbon decarbonylation products and RhCl(CO)(PPh3)2 were also formed. 3-Methyl-4-pentenal was isomerized to 3-methylcyclopentanone by 1. 4-Hexenal possessing deuterium at C-2 was isomerized to 2 which contained deuterium at C-5. trans-4-Hexenal-1-d was cyclized to 2-3-d and 2-2-d in 9:1 ratio when the reaction was carried to a low conversion.The deuterium in the 2-3-d product was found to be cis to the C-2 CH3 group. cis-4-Hexenal-1-d was isomerized by 1 to afford 2-3-d possessing deuterium trans to the C-2 CH3 group.NMR analyses of these products were assisted by the synthesis and characterization of 2-cis-2,3-d2 by treatment of 2-methylcyclopent-2-en-1-one with D2 and 1.The 2-cis-2,3-d2 could be converted to a 1:1 mixture of 2-3-d diastereomers on treatment with HCl in MeOH/H2O.The result demonstrated that the cyclization of 4-hexenal-1-d occurred by a syn addition of the C-D bond to the olefinic bond to generate 2-3-d.The presence of C2H4 in reactin mixtures of 1 and 4-hexenal-1-d resulted in the formation of substantial 2-d0 and C2H3D.The deuterium locations in the 1-pentene, 2-pentene, and ethylcyclopropane decarbonylation products derived from reaction of 4-hexenal-1-d with 1 were determined.The results were interpreted in terms of a hydroacylation mechanism involving an acylrhodium(III) hydride complex and organometallic intermediates derived therefrom.The hydroacylation and decarbonylation products appear to be generated via common intermediates.
- Campbell, Richard E.,Lochow, Charles F.,Vora, Krishnakant P.,Miller, Roy G.
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- Faujasite silicalites for oxidative dehydrogenation of n-octane: Influence of alkali metals, gallium, and boron on catalyst activity
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The sol-gel method was used to synthesize faujasite type silicalites bearing gallium and boron in the framework. Barium and sodium were used as charge balancing cations since isomorphic substitution of Si4+ by Ga3+ or B3+ results in a negative excess charge of the framework. The successful synthesis of this type of silicalites (GaBaY-S, BBaY-S, GaBBaY-S(IE), GaNaY-S) was confirmed using powder-XRD. SEM analysis showed that the morphology of the catalysts with respect to particle size depended on the framework metals and the charge balancing cation used. Framework Ga containing catalysts showed smaller particle size compared to B containing catalysts. Sodium also yielded a smaller particle-sized catalyst compared to barium. The catalysts were tested in the continuous flow oxidative dehydrogenation (ODH) of n-octane, and the catalytic results showed dependence on the active metal reducibility and acid-base character of the catalysts. At iso-conversion of 8 ± 1 %, the least acidic BBaY-S gave the highest selectivity to octenes (40 %) and the lowest selectivity to COx (28 %), and the most acidic GaNaY-S showed the opposite results with octenes at 17 % and COx at 56 %. The catalysts (BaBY-S and GaBBaY-S(IE) with least total acidity had the greatest quantity of strong acid sites which were attributed to Lewis acid sites, confirmed by the pyridine IR analysis. The GaNaY-S, with the highest total acidity, had the least strong acid sites.
- Ndlela, Siyabonga S.,Friedrich, Holger B.,Cele, Mduduzi N.
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- On the product formation in 1-Butene metathesis over supported tungsten catalysts
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1-Butene metathesis was performed over 8 wt% tungsten catalysts supported on silica, silica-alumina and γ-Al2O3. Under the applied reaction conditions, 1-butene metathesis yields with a relatively large selectivity iso-butene in addition to the expected metathesis products. The isobutene selectivity is high for catalysts with a relative low activity and decreases with increasing metathesis activity. It is deduced that iso-butene formation involves surface tungsten complexes, whose formation inhibits the metathesis activity. Springer Science+Business Media, LLC 2010.
- Harmse, Liesel,Van Schalkwyk, Charl,Van Steen, Eric
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- Photolysis of heptanal
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Photolysis of heptanal is investigated from an experimental and theoretical point of view. Photoexcited heptanal is believed to undergo rapid intersystem crossing to the triplet manifold and from there undergoes internal H-abstraction to form biradical intermediates. The favored γ-H abstraction pathway can cyclize or cleave to 1-pentene and hydroxyethene, which tautomerizes to acetaldehyde. Yields of 1-pentene and acetaldehyde were measured at 62 ± 7% and 63 ± 7%, respectively, relative to photolyzed heptanal. Additionally, small quantities of hexanal and hexanol were observed. On the basis of combined experimental and theoretical evidence, the remaining heptanal photolysis proceeds to form an estimated 10% HCO + hexyl radical and 30% cyclic alcohols, particularly 2-propyl cyclobutanol and 2-ethyl cyclopentanol.
- Paulson, Suzanne E.,Liu, De-Ling,Orzechowska, Grazyna E.,Campos, Luis M.,Houk
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- The Selective Conversion of n-Pentane into Pent-1-ene via Trihydro(trans-penta-1,3-diene)bis(triarylphosphine)rhenium
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Treatment of n-pentane with heptahydridobis(triarylphosphine)rhenium and 3,3-dimethylbutene gives trihydrido(trans-penta-1,3-diene)bis(triarylphosphine)rhenium; trimethyl phosphite converts this, with high selectivity, into pent-1-ene.
- Baudry, Denise,Ephritikhine, Michael,Felkin, Hugh,Zakrzewski, Janusz
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- Intramolecular Trapping of Alkyl- and Arylrhodium Hydride Intermediates in the Decarbonylation of Aldehydes by Chlorotris(triphenylphosphine)rhodium
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The reaction of 5-hexenal with RhCl(PPh3)3 (1) or 2 (5) gives some cyclopentane.The reaction of 2-allylbenzaldehyde with 5 gives a good yield of indan.These cyclization reactions to give cyclopentanes, and other reactions of Δ4-enals to give cyclopropanes, reveal the presence of intermediate alkyl- and arylrhodium hydride complexes on the pathway for decarbonylation of aldehydes.The formation of nortricyclene from endo-5-norbornene-2-carboxaldehyde shows that the alkylrhodium hydride must be formed with retention of stereochemistry at the α-carbon of the aldehyde.
- Kampmeier, J. A.,Harris, S. H.,Mergelsberg, I
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- Photolysis and Radiolysis of Cyclopentane in the Liquid Phase
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The liquid-phase photolysis of cyclopentane has been investigated at energies below (7.6, 8.4 eV) and above (10.0, 11.6 eV) the ionization threshold (8.7 eV).The molecules excited by photon absorption and by charge recombination undergo four major dissoci
- Ausloos, P.,Lias, S. G.,Rebbert, R. E.
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- Pyrolysis of hexadecane
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The kinetics of thermal decomposition of hexadecane was studied in a flow tubular reactor from stainless steel. The experiments were performed in the temperature range of 700 to 780°C for the mass ratio of steam to hydrocarbon 3 : 1. The hexadecane pyrolysis took place according to the first-order reaction with a frequency factor of 3.5 . 109 s-1 and an activation energy of 162 kJ mol-1. In the pyrolysis products there were above all 1-alkenes. From alkanes, methane and ethane and less propane were formed in a higher degree. The prevailing compounds are ethene and propene whose amount increases with increasing temperature and residence time. The content of 1-alkenes higher than 1-pentene decreases with increasing conversion which gives evidence of their decomposition owing to their lower stability in comparison with the lighter 1-alkenes. The formation of dienes (1,3-butadiene and propadiene) and benzene also confirmed the course of secondary reactions. The observed higher formation of hydrogen results from the reaction of steam with coke deposited on the walls of the reactor or with hydrocarbon radicals. The evidence of the coke formation is given also by the presence of carbon oxides whose amount grew with the pyrolysis severity. The high content of 1-hexene in comparison with the other higher 1-alkenes is probably caused by the isomerization of alkyl radicals by 1,5-hydrogen transfer.
- Bartekova, Elena,Bajus, Martin
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- On the Mechanism of Oligomerization of Propylene by (C5Me5)2MCl2/Methylalumoxane Catalysts (M=Zr, Hf)
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In the oligomerization of propylene by (C5Me5)2MCl2 (M=Zr, Hf)/methylalumoxane, formation of abnormal oligomers such as 1-pentene(C5), 2,4-dimethyl-1-pentene(C7), 4-methyl-1-heptene(C8), and 2,4,6-trimethyl-1-heptene(C10) besides normal oligomers such as 4-methyl-1-pentene(C6) and 4,6-dimethyl-1-heptene(C9) is indicative of the mixing of unusual β-CH3 and usual β-H transfer terminations from each growing carbon chain which was initiated by insertion of propylene into either M-H or M-Me bond.
- Mise, Takaya,Kageyama, Akiko,Miya, Shinya,Yamazaki, Hiroshi
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- Synthesis of (8E, 10Z)-tetradeca-8, 10-dienal, sex pheromone of horse chestnut leafminer (Cameraria ohridella), and all its geometrical isomers
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(8E,10Z)-Tetradeca-8, 10-dienal (1a), sex pheromone of the horse chestnut leafminer (Cameraria ohridella; Lepidoptera, Gracillariidae), and its geometrical isomers (1b-1d) were efficiently synthesized using tetrakis(triphenylphosphine)palladium catalyzed cross-coupling reactions of alk-1-ynes or alkenyl alanes with corresponding vinyl iodides. The stereoisomeric purity of obtained tetradecadienals 1a-1d was higher than 95% (GC). Relative electroantennographic (EAG) activities of the prepared compounds 1a-1d elicited on male antennae supported the previously published identification of the C. ohridella sex pheromone.
- Hoskovec, Michal,Saman, David,Svatos, Ales
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- Pt/[Fe]ZSM-5 modified by Na and Cs cations: An active and selective catalyst for dehydrogenation of n-alkanes to n-alkenes
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Pt clusters within [Fe]ZSM-5 channels provide active and stable sites for the selective catalytic dehydrogenation of n-alkanes to n-alkenes. Cs and Na cations titrate acid sites and inhibit skeletal isomerization and cracking side reactions. The Royal Soc
- Li, Xuebing,Iglesia, Enrique
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- Infrared-Laser-Induced Gas-Phase Isomerization of Olefins in the Presence of Fe(CO)5
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Irradiation of a mixture of 1-pentene or trans-2-pentene and Fe(CO)5 with a pulsed CO2 TEA laser at low pressures in the vapor phase results in the formation of isomeric mixtures of 1- and 2-pentenes and the consumption of Fe(CO)5.Isomerization occurs due to heating of the Fe(CO)5 caused by collisional deactivation of the excited pentene.This results in decomposition of Fe(CO)5 to yield chemically reactive coordinatively unsaturated iron carbonyls or iron atoms which can effect the cis, trans and positional isomerization of olefins.Both the initial and final pentene isomer ratios differ significantly from those observed in solution phase photochemically or in thermally initiated isomerization of the pentenes by iron carbonyls.
- Teng, Peter A.,Lewis, Frederick D.,Weitz, Eric
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- Homogeneous catalytic transfer dehydrogenation of alkanes with a group 10 metal center
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Unambiguous catalytic homogeneous alkane transfer dehydrogenation was observed with a group 10 metal complex catalyst, LPtII(cyclo-C 6H10)H, supported by a lipophilic dimethyl-di(4-tert- butyl-2-pyridyl)borate anionic ligand and tert-butylethene as the sacrificial hydrogen acceptor.
- Khaskin, Eugene,Lew, Daniel L.,Pal, Shrinwantu,Vedernikov, Andrei N.
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- Preparation, properties, and reactions of metal-containing heterocycles. 73. The bis(triflate) route to rhenacycloalkanes
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The metallacycloalkanes CpRe(CO)2(CH2)5 (2) and CpRe(CO)2(CH2)4 (3) (Cp = η5-C5H5) have been prepared by cationic alkylation of CpRe(CO)2H2
- Lindner, Ekkehard,Wassing, Walter
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- Catalytic dehydroisomerization of n-alkanes to isoalkenes
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An equilibrated mixture of pentene isomers was produced by dehydroisomerization of n-pentane on catalysts consisting of Pt clusters within [Fe]ZSM-5 channels. These catalysts showed high isomerization rates, excellent stability even without added H2
- Li, Xuebing,Iglesia, Enrique
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- THE DIRECT PHOTO-OXIDATIVE DECARBOXYLATION OF α-OXO-CARBOXYLIC ACIDS
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α-Oxo-carboxylic acids undergo photo-oxidative decarboxylation from both C-1 and C-2 positions, and reaction does not involve singlet oxygen: a mechanism involving an electron transfer reaction is postulated.
- Davidson, Stephen R.,Goodwin, Dean,Turnock, Geoffrey
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- The gas-phase oxidation of n-hexadecane
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Since n-hexadecane or cetane is a reference fuel for the estimation of cetane numbers in diesel engines, a detailed chemical model of its gas-phase oxidation and combustion will help to enhance diesel performance and reduce the emission of pollutants at t
- Fournet,Battin-Leclerc,Glaude,Judenherc,Warth,Come,Scacchi,Ristori,Pengloan,Dagaut,Cathonnet
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- Dehydrobromination of Secondary and Tertiary Alkyl and Cycloalkyl Bromides with 1,8-Diazabicycloundec-7-ene. Synthetic Applications
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The alkene proportions from the dehydrohalogenation of eight secondary and six tertiary aliphatic bromides, four 1-bromo-1-alkylcycloalkanes, three dibromobutanes, and 2-hexyl chloride and iodide with the hindered amidine 1,8-diazabicycloundec-7-ene (DBU) have been determined.For secondary bromides, the ratios of the more substituted alkene (Saytzeff product) to less substituted alkene (Hofmann product) are on the order of 9:1; for tertiary bromides, the corresponding ratios are 2-3:1 for aliphatic systems and >6:1 for cycloalkyl systems.The presence of a tertiary or benzylic β-H favors the Saytzeff product.Chain branching or elongation of the tertiary aliphatic bromides has only a small effect upon the regioselectivity.Activation of the β-H with a bromine atom considerably reduces the regioselectivity.For 2-halohexanes, the proportion of Saytzeff product increases in the order chloride bromide iodide, while the trans/cis ratio increases in the same order from 4.9 to 9.Reduced regio- and stereoselectivities were observed when 2-hexyl p-toluenesulfonate was treated with DBU.The thermolysis of the same compound gave a mixture of 1-, 2-, and 3-hexene
- Wolkoff, Peder
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- Room temperature dehydrogenation of ethane to ethylene
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The transient titanium alkylidyne, (PNP)Ti≡CtBu (PNP = N[2-PiPr2-4-methylphenyl]2-), activates a C-H bond of ethane at room temperature, and a β-hydrogen of the resulting ethyl ligand is subsequently transferred to the adjacent alkylidene ligand to form an ethylene adduct of titanium. Treatment of the ethylene complex with two-electron oxidants such as organic azides results in extrusion of ethene concomitant with formation of a mononuclear titanium imido complex.
- Cavaliere, Vincent N.,Crestani, Marco G.,Pinter, Balazs,Pink, Maren,Chen, Chun-Hsing,Baik, Mu-Hyun,Mindiola, Daniel J.
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- HYDROGENATION OF CONJUGATED DOUBLE BONDS OF trans-1,3-PENTADIENE CATALYZED BY Rh2Cl2(CO)4 IN SOLUTION AND ANCHORED TO γ-Al2O3
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Hydrogenation under mild conditions (1 atm H2 and 60-80 deg C) of trans-1,3-pentadiene catalysed by Rh2Cl2(CO)4 in toluene solution and by Rh2Cl2(CO)4 anchored on γ-Al2O3 has been investigated.Both the homogeneous and the heterogenised catalysts display a good specificity towards hydrogenation of the external double bond of the conjugated diene system.A slow inactivation of the supported catalyst occurs during the hydrogenation, but it cannot be attributed to reaction of the catalyst with the substrate since it occurs also when Rh2Cl2(CO)4 is heated at 70 deg C under 1 atm H2.Partial substitution of CO ligands of Rh2Cl2(CO)4 by triphenylphosphine leads to a reduction of the activity of the homogeneous catalyst but does not alter its specificity.Triphenylphosphine can either increase or decrease the activity of the heterogenised catalyst depending on whether its introduction into the system precedes or follows the anchorage of Rh2Cl2(CO)4 on Al2O3.
- Lausarot, P. Michelin,Vaglio, G. A.,Valle, M.
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- The Regiochemistry of Cyclopropylcarbinylstannane Ring Fission.
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The reaction of 2-methylcyclopropylcarbinyltrimethylstannane 1 in chloroform with the electrophiles sulphur dioxide, trifluoroacetic acid, and iodine proceeds preferentially with ring cleavage and addition at the unsubstituted cyclopropyl methylene.Iodination and acidolysis in methanol proceeds exclusively with tin-methyl bond cleavage.
- Lucke, Andrew J.,Young, David J.
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- PENTENE FORMATION FROM PROPIONALDEHYDE ADSORBED ON Rh-Y ZEOLITE
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Pentene formation is observed during desorption of propionaldehyde from Rh-Y zeolite into a helium stream, while neither Na-Y zeolite nor H-Na-Y zeolite is effective for pentene formation.
- Takahashi, Nobuo,Sato, Yoshio,Kobayashi, Masayoshi
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- CATALYTIC HYDROGENATION OF 1,3-trans-PENTADIENE OVER Rh4(CO)12 SUPPORTED ON γ-Al2O3
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Rh4(CO)12 anchored on γ-Al2O3 (Rh4(CO)12/Al2O3) has been studied as a catalyst for the hydrogenation of 1,3-trans-pentadiene.Under mild conditions (1 atm H2 and temperatures between 60 deg C and 80 deg C) hydrogenation occurs at only one of the double bonds of the diene, and analysis of the products shows that the terminal double bond is preferentially hydrogenated.Hydrogenation of the second double bond of the conjugated diene occurring only after all the 1,3-trans-pentadiene has been consumed.In this respect Rh4(CO)12/Al2O3 behaves like toluene solutions of Rh4(CO)12.Anchoring of Rh4(CO)12 on the solid support gives a catalyst which is less active but more stable than toluene solutions of Rh4(CO)12.The effects of CO and of triphenylphosphine on catalytic activity and on specificity of Rh4(CO)12/Al2O3 have also been investigated and both shown to cause a reduction of the rate of hydrogenation of 1,3-trans-pentadiene.
- Lausarot, P. Michelin,Vaglio, G. A.,Valle, M.
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- RATIONAL TEST FOR POSSIBLE ZINCACYCLOBUTANE ION IN THE GUSTAVSON REACTION
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The possibility of obtaining a zincacyclobutane intermediate in the Gustavson reaction was hypothesized to explain the formation of olefins obtained in this reaction.A select group of substrates was investigated in which the formation of olefin products could be explained if one invoked the intermediacy of a zincacyclobutane, but would be difficult to explain in the absence of such an intermediate.A deuterium-labeled substrate was also investigated and the olefins obtained from its reaction with zinc were found to closely follow the deuterium-labeling pattern obtainedfrom the decomposition of the analogous deuterium-labeled platinacyclobutane.
- Johnson, Thomas H.,Hefty, Elaine C.
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- Heavy ion radiolysis of cyclopentane
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The radiolysis of neat and iodine solutions of cyclopentane has been performed with 1-15 MeV protons, 5-20 MeV helium ions, 12-31 MeV carbon ions, and 22-32 MeV oxygen ions. The yields of the major products cyclopentene, bicyclopentyl, 1-pentene, and cyclopentyl iodide as well as the yields of a few select minor products have been determined. All products show a decrease in yield with increasing linear energy transfer (LET) of the irradiating particle. Some of these decreases are very large: for instance, the observed drop in the yield of bicyclopentyl from γ-rays (LET = 0.14 eV/nm) to oxygen ions (LET = 900 eV/nm) amounts to a net loss of about 4 cyclopentyl radicals/100 eV absorbed energy. This value is 80% of the total cyclopentyl radicals produced in γ-radiolysis. There are some indications that the yields of radicals due to decomposition of excited cyclopentane molecules are dependent on the energy and type of irradiating particle.
- Wojnarovits,La Verne
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- SELECTIVE HYDROGENATION OF CARBON MONOXIDE ON SUPPORTED Rh CATALYSTS PREREDUCED IN SITU WITH H2O AND CO OR H2
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Carbon monoxide was selectively converted to ethylene and propylene (>80percent of C1-C6 hydrocarbons produced) at 433-447 K over SiO2-supported Rh catalyst prereduced in situ with a CO-H2O mixture, while another Rh catalyst obtained by the pretreatment in situ with a H2-H2O mixture yielded ethanol and acetaldehyde at a higher selectivity by a factor of about 100 at 453 K than a usual Rh(0) catalyst reduced with H2 alone.
- Iwasawa, Yasuhiro,Hayasaka, Toshiaki,Ogasawara, Sadao
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- Formation of olefins upon oxidation of molybdenum alkyl carbynes. Organic radical reactivity in an organometallic radical cation
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Decomposition of the complexes (η5-C5H5)(CO){P(OMe) 3}Mo≡CR [R = C-C4H9, (CH2)3CH3, and CH(CH2-CH2CH3)2] in CHCl3 results in conversion of the carbyne ligand to a terminal olefin. The reaction is initiated by oxidation and occurs during photolysis in CHCl3 or upon slow diffusion of O2 into the reaction mixtures. Corroborating evidence for initiation of the reaction by electron transfer has been obtained by conversion of the butyl carbyne ligand of (η5-C5H5)(CO){P(OMe) 3}Mo≡C(CH2)3CH3 to 1-pentene upon electrochemical oxidation. Mechanistic studies were consistent with H-abstraction by the carbyne radical cation to yield a cationic carbene complex which forms the olefin in a H-shift process. INDO calculations on the carbyne radical cation [(η5-C5H5)(CO){P(OMe) 3}-Mo≡CCH2CH3]?+ indicate stabilization upon bending the Mo≡C-C angle from 180° to 120°. This change in geometry places spin density on the carbyne carbon in the radical cation although the initial oxidation occurs from an orbital that is primarily nonbonding metal d in character. The oxidized carbyne is thus able to function as a carbon-centered radical and abstract a hydrogen atom at the carbyne carbon. Although the olefin-forming reaction is general for alkyl carbynes with a hydrogen on C2, the tert-butyl carbyne (η5-C5H5)(CO){P(OMe) 3}Mo≡CC-(CH3)3 (2e) did not form an olefin upon oxidation. Instead, photolysis of 2e in CHCl3 yielded the dicnloromolybdenum carbyne (η5-C5H5)Cl2{P(OMe) 3}Mo≡CC(CH3)3 (5e) via a Cl-abstraction pathway.
- Schoch, Thomas K.,Orth, Stephen D.,Zerner, Michael C.,J?rgensen, Karl Anker,McElwee-White, Lisa
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- Tethering of a Phosphinidene Stabilised Cluster to Oxide Supports
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The complex (μ-H)2Ru3(CO)93-PCH2CH2Si(OEt)3> (1a) has been supported on SiO2, Al2O3, TiO2, MgO, and ZnO; the phosphinidene ligand stabilises the cluster under catalytic conditions.
- Cook, Stephen L.,Evans, John
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- Selective aerobic oxidation in supercritical carbon dioxide catalyzed by the H5PV2Mo10O40 polyoxometalate
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Selective aerobic oxidation of benzylic alcohols and of activated aromatic hydrocarbons occurs in supercritical CO2 as reaction medium using H5PV2Mo10O40 as a quasi-heterogeneous catalyst without further additives or co-solvents; efficient recycling is possible and no metal leaching is detectable in the product stream. The Royal Society of Chemistry 2006.
- Maayan, Galia,Ganchegui, Benjamin,Leitner, Walter,Neumann, Ronny
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- A durable nanocatalyst of potassium-doped iron-carbide/alumina for significant production of linear alpha olefins via Fischer-Tropsch synthesis
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Improvement of activity, selectivity, and stability of the catalyst used in Fischer-Tropsch synthesis (FTS) to produce targeted hydrocarbon products has been a major challenge. In this work, the potassium-doped iron-carbide/alumina (K-Fe5C2/Al2O3), as a durable nanocatalyst containing small iron-carbide particles (～ 10 nm), was applied to high-temperature Fischer-Tropsch synthesis (HT-FTS) to optimize the production of linear alpha olefins. The catalyst, suitable under high space velocity reaction conditions (14–36 N L gcat?1 h?1) based on the well-dispersed potassium as an efficient base promoter on the active iron-carbide surface, shows very high CO conversion (up to ～90%) with extremely high activity (1.41 mmolCO gFe?1 s?1) and selectivity for C5–C13 linear alpha olefins.
- Park, Ji Chan,Jang, Sanha,Rhim, Geun Bae,Lee, Jin Hee,Choi, Hyunkyoung,Jeong, Heon-Do,Youn, Min Hye,Lee, Dong-Wook,Koo, Kee Young,Kang, Shin Wook,Yang, Jung-Il,Lee, Ho-Tae,Jung, Heon,Kim, Chul Sung,Chun, Dong Hyun
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- A Photochemical Source of Real Alkylcarbenes
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Treatment of 7,7-dibromodibenzobicycloheptane with di-tert-butylcuprate or dibutylcuprate, followed by quenching with water, led to exo- and endo-7-monoalkyldibenzobicycloheptanes.Photolysis through either quartz or Pyrex gave the products of intramolecular reactions of the corresponding alkylcarbenes.The temperature dependence of the products formed from tert-butylcarbene was verified, and butylcarbene was trapped intermolecularly. - Keywords: carbenes, retrocycloadditions, insertion reactions.
- Glick, HC,Likhotvorik, Igor R.,Jones, Maitland
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- Production of renewable 1,3-pentadiene over LaPO4 via dehydration of 2,3-pentanediol derived from 2,3-pentanedione
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1,3-Pentadiene plays an extremely important role in the production of polymers and fine chemicals. Herein, the LaPO4 catalyst exhibits excellent catalytic performance for the dehydration production of 1,3-pentadiene with 2,3-pentanediol, a C5 diol platform compound that can be easily obtained by hydrogenation of bio-based 2,3-pentanedione. The relationships of catalyst structure-acid/base properties-catalytic performance was established, and an acid-base synergy effect was disclosed for the on-purpose synthesis of 1,3-pentadiene. Thus, a balance between acid and base sites was required, and an optimized LaPO4 with acid/base ratio of 2.63 afforded a yield of 1,3-pentadiene as high as 61.5% at atmospheric pressure. Notably, the Br?nsted acid sites with weak or medium in LaPO4 catalyst can inhibit the occurrence of pinacol rearrangement, resulting in higher 1,3-pentadiene production. In addition, the investigation on reaction pathways demonstrated that the E2 mechanism was dominant in this dehydration reaction, accompanied by the assistance of E1 and E1cb.
- Bai, Chenxi,Cui, Long,Dai, Quanquan,Feng, Ruilin,Liu, Shijun,Qi, Yanlong
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- CATALYTIC HYDROCARBON DEHYDROGENATION
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A catalyst for dehydrogenation of hydrocarbons includes a support including zirconium oxide and Linde type L zeolite (L-zeolite). A concentration of the zirconium oxide in the catalyst is in a range of from 0.1 weight percent (wt. %) to 20 wt. %. The catalyst includes from 5 wt. % to 15 wt. % of an alkali metal or alkaline earth metal. The catalyst includes from 0.1 wt. % to 10 wt. % of tin. The catalyst includes from 0.1 wt. % to 8 wt. % of a platinum group metal. The alkali metal or alkaline earth metal, tin, and platinum group metal are disposed on the support.
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Paragraph 0061; 0062; 0122; 0123
(2021/03/13)
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- Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
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Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
- Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
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p. 1996 - 2003
(2020/04/22)
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- Method for eliminating hydrogen chloride by catalytic cracking of chloralkane
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The invention discloses a method for eliminating hydrogen chloride by catalytic cracking of chloralkane, comprising the following steps of: carrying out a cracking reaction on chloralkane under the action of a biomass-based nitrogen-doped carbon catalyst to eliminate hydrogen chloride so as to prepare corresponding olefin, wherein the biomass-based nitrogen-doped carbon catalyst is prepared by carbonizing biomass or a mixture of biomass and a nitrogen source at 400-1000 DEG C, and the biomass is selected from at least one of bamboo processing leftovers, wood processing leftovers, plant straws,plant leaves, cereals, beans, cereal processing leftovers, bean processing leftovers and livestock manure. The method disclosed by the invention has the advantages of simple preparation process, easily available raw materials, low cost, strong process controllability, easiness in large-scale production, high catalytic cracking conversion rate of the chloralkane, high product selectivity, low energy consumption and the like.
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Paragraph 0142-0147
(2020/08/06)
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- Competitive adsorptions between thiophenic compounds over a CoMoS/Al2O3 catalyst under deep HDS of FCC gasoline
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The transformation of various model sulfur compounds (2-methylthiophene: 2MT, 3-methylthiophene: 3MT and benzothiophene: BT) representative of sulfur compounds in FCC gasoline was investigated over a CoMoS/Al2O3 catalyst. More specifically, a quantitative reactivity scale was established with BT being more reactive than 3MT and 2MT. In mixture, their reactivity was reduced due to the presence of the other sulfur compound, the scale of reactivity being preserved. BT strongly inhibits the transformation of 2MT. With a single kinetic model based on a Langmuir Hinshelwood formalism, kinetic and adsorption parameters were calculated and the results explained by mutual competitive adsorption between 2MT and BT with a higher adsorption constant for BT compared to that of 2MT.
- dos Santos, Alan Silva,Girard, Etienne,Leflaive, Philibert,Brunet, Sylvette
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p. 292 - 298
(2018/12/11)
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- Hydrocarbon Synthesis via Photoenzymatic Decarboxylation of Carboxylic Acids
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A recently discovered photodecarboxylase from Chlorella variabilis NC64A (CvFAP) bears the promise for the efficient and selective synthesis of hydrocarbons from carboxylic acids. CvFAP, however, exhibits a clear preference for long-chain fatty acids thereby limiting its broad applicability. In this contribution, we demonstrate that the decoy molecule approach enables conversion of a broad range of carboxylic acids by filling up the vacant substrate access channel of the photodecarboxylase. These results not only demonstrate a practical application of a unique, photoactivated enzyme but also pave the way to selective production of short-chain alkanes from waste carboxylic acids under mild reaction conditions.
- Zhang, Wuyuan,Ma, Ming,Huijbers, Mieke M. E.,Filonenko, Georgy A.,Pidko, Evgeny A.,Van Schie, Morten,De Boer, Sabrina,Burek, Bastien O.,Bloh, Jonathan Z.,Van Berkel, Willem J. H.,Smith, Wilson A.,Hollmann, Frank
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supporting information
p. 3116 - 3120
(2019/03/06)
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- Cobalt-Iron-Manganese Catalysts for the Conversion of End-of-Life-Tire-Derived Syngas into Light Terminal Olefins
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Co-Fe-Mn/γ-Al2O3 Fischer–Tropsch synthesis (FTS) catalysts were synthesized, characterized and tested for CO hydrogenation, mimicking end-of-life-tire (ELT)-derived syngas. It was found that an increase of C2-C4 olefin selectivities to 49 % could be reached for 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn/γ-Al2O3 with Na at ambient pressure. Furthermore, by using a 5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al2O3 catalyst the selectivity towards the fractions of C5+ and CH4 could be reduced, whereas the selectivity towards the fraction of C4 olefins could be improved to 12.6 % at 10 bar. Moreover, the Na/S ratio influences the ratio of terminal to internal olefins observed as products, that is, a high Na loading prevents the isomerization of primary olefins, which is unwanted if 1,3-butadiene is the target product. Thus, by fine-tuning the addition of promoter elements the volume of waste streams that need to be recycled, treated or upgraded during ELT syngas processing could be reduced. The most promising catalyst (5 wt % Co, 5 wt % Fe, 2.5 wt % Mn, 1.2 wt % Na, 0.03 wt % S/γ-Al2O3) has been investigated using operando transmission X-ray microscopy (TXM) and X-ray diffraction (XRD). It was found that a cobalt-iron alloy was formed, whereas manganese remained in its oxidic phase.
- Falkenhagen, Jan P.,Maisonneuve, Lise,Paalanen, Pasi P.,Coste, Nathalie,Malicki, Nicolas,Weckhuysen, Bert M.
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supporting information
p. 4597 - 4606
(2018/03/06)
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- An Engineered Self-Sufficient Biocatalyst Enables Scalable Production of Linear α-Olefins from Carboxylic Acids
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Fusing the decarboxylase OleTJE and the reductase domain of P450BM3 creates a self-sufficient protein, OleT-BM3R, which is able to efficiently catalyze oxidative decarboxylation of carboxylic acids into linear α-olefins (LAOs) under mild aqueous conditions using O2 as the oxidant and NADPH as the electron donor. The compatible electron transfer system installed in the fusion protein not only eliminates the need for auxiliary redox partners, but also results in boosted decarboxylation reactivity and broad substrate scope. Coupled with the phosphite dehydrogenase-based NADPH regeneration system, this enzymatic reaction proceeds with improved product titers of up to 2.51 g L-1 and volumetric productivities of up to 209.2 mg L-1 h-1 at low catalyst loadings (～0.02 mol%). With its stability and scalability, this self-sufficient biocatalyst offers a nature-friendly approach to deliver LAOs.
- Lu, Chen,Shen, Fenglin,Wang, Shuaibo,Wang, Yuyang,Liu, Juan,Bai, Wen-Ju,Wang, Xiqing
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p. 5794 - 5798
(2018/06/01)
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- Terminal alkyne insertion into a thiolate-bridged dirhodium hydride complex derived from heterolytic cleavage of H2
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Thiolate-bridged dirhodium and diiridium complexes can facilely realize heterolytic cleavage of H2 across the metal-sulfur bond to generate the corresponding hydride bridged complexes. Furthermore, terminal alkynes can insert the Rh-H-Rh fragment to afford σ:π alkenyl bridged complexes and then convert to the corresponding alkenes in the presence of a reductant and an acid.
- Zhao, Xiangyu,Yang, Dawei,Zhang, Yahui,Wang, Baomin,Qu, Jingping
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supporting information
p. 11112 - 11115
(2018/10/15)
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- Interactions of C?F Bonds with Hydridoboranes: Reduction, Borylation and Friedel–Crafts Alkylation
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The stoichiometric reactions of the alkylfluorides 1-fluoroadamantane (Ad-F), fluorocyclohexane (Cy-F), 1-fluoropentane (Pent-F) and benzyl fluorides with secondary boranes pinacolborane (HBpin), catecholborane (HBcat), 9-borabicyclo(3.3.1)nonane (9-BBN)
- Bamford, Karlee L.,Chitnis, Saurabh S.,Qu, Zheng-wang,Stephan, Douglas W.
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supporting information
p. 16014 - 16018
(2018/10/15)
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- Stereoselectivity in a series of 7-alkylbicyclo[3.2.0]hept-2-enes: Experimental and computational perspectives
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Rate constants for overall decomposition (kd) for a series of exo-7-alkylbicyclo[3.2.0]hept-2-enes are relatively invariant. For the alkyl substituents ethyl, propyl, butyl, isopropyl, and t-butyl, the ratio of the rate constant for [1,3] sigmatropic rearrangement to the rate constant for fragmentation, k13/kf, is significantly lower than k13/kf?=?150 observed for exo-7-methylbicyclo[3.2.0]hept-2-ene. Regardless of the size and mass of the alkyl group, the stereoselectivity of the [1,3] carbon migration appears to be quite stable at 80% to 89% suprafacial inversion (si), an observation consistent with conservation of angular momentum but not conservation of orbital symmetry. This global result comports with the phenomenon of “dynamic matching” espoused by Carpenter and collaborators for [1,3] sigmatropic rearrangements in general.
- Leber, Phyllis,Kidder, Katherine,Viray, Don,Dietrich-Peterson, Eric,Fang, Yuan,Davis, Alexander
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- Alkanethiolate-capped palladium nanoparticles for selective catalytic hydrogenation of dienes and trienes
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Selective hydrogenation of dienes and trienes is an important process in the pharmaceutical and chemical industries. Our group previously reported that the thiosulfate protocol using a sodium S-alkylthiosulfate ligand could generate catalytically active Pd nanoparticles (PdNP) capped with a lower density of alkanethiolate ligands. This homogeneously soluble PdNP catalyst offers several advantages such as little contamination via Pd leaching and easy separation and recycling. In addition, the high activity of PdNP allows the reactions to be completed under mild conditions, at room temperature and atmospheric pressure. Herein, a PdNP catalyst capped with octanethiolate ligands (C8 PdNP) is investigated for the selective hydrogenation of conjugated dienes into monoenes. The strong influence of the thiolate ligands on the chemical and electronic properties of the Pd surface is confirmed by mechanistic studies and highly selective catalysis results. The studies also suggest two major routes for the conjugated diene hydrogenation: the 1,2-addition and 1,4-addition of hydrogen. The selectivity between two mono-hydrogenation products is controlled by the steric interaction of substrates and the thermodynamic stability of products. The catalytic hydrogenation of trienes also results in the almost quantitative formation of mono-hydrogenation products, the isolated dienes, from both ocimene and myrcene.
- Chen, Ting-An,Shon, Young-Seok
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p. 4823 - 4829
(2017/10/19)
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- Multiple C-H Activations of Linear Alkanes by Various (??5-Cyclopentadienyl)W(NO)(CH2CMe3)2 Complexes
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As illustrated in the accompanying diagram, thermolysis of Cp?W(NO)(CH2CMe3)2 (Cp? = n5-C5Me5) at 80 °C in neat linear alkanes effects three successive C-H bond activations of the hydrocarbon substrates and forms Cp?W(NO)(H)(n3-allyl) complexes in which the allyl ligands are derived from the alkanes. These allyl hydrido compounds exist in solutions as mixtures of isomers containing monosubstituted (i.e., terminal) or 1,3-disubstituted (i.e., internal) allyl ligands which can have either an endo or exo orientation with the substituent groups being either proximal or distal to the nitrosyl ligand. Due to steric factors the most abundant isomer in all cases has a monosubstituted allyl ligand in the endo orientation with the alkyl end distal to the nitrosyl ligand. In addition, the relative abundance of Cp?W(NO)(H)(n3-allyl) isomers having monosubstituted allyl ligands decreases with increasing length of the n-alkane chain. Further thermolysis of the Cp?W(NO)(H)(n3-allyl) complexes results in the liberation of alkenes. Whether initiated by Cp?W(NO)(CH2CMe3)2 or independently synthesized Cp?W(NO)(H)(n3-allyl) complexes, the n-alkane dehydrogenations generally result in the preferential formation of 1-alkenes. They are stoichiometric, and their outcomes are not significantly affected by varying the experimental conditions employed (e.g., time, temperature, an open system, use of an H2 acceptor, etc.) or by changing the initial bis(neopentyl) tungsten reactant to its CpEt (n5-C5Me4Et) and CpiPr (n5-C5H4iPr) analogues or to Cp?Mo(NO)(CH2CMe3)2. The results of DFT calculations are consistent with these dehydrogenations proceeding via 16e Cp?M(NO)(n2-alkene) (M = Mo, W) intermediates that are in equilibrium with their more stable 18e Cp?M(NO)(H)(n3-allyl) isomers. These intermediates facilitate the allyl ligand exchange reactions depicted in the accompanying diagram by functioning as internal hydrogen acceptors during the dehydrogenation of the linear alkanes. Thermolysis of the final hydrido allyl complexes liberates the desired alkenes.
- Shree, Monica V.,Fabulyak, Diana,Baillie, Rhett A.,Lefèvre, Guillaume P.,Dettelbach, Kevan,Béthegnies, Aurélien,Patrick, Brian O.,Legzdins, Peter,Rosenfeld, Devon C.
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supporting information
p. 2714 - 2726
(2017/08/21)
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- Investigation of deep catalytic cracking of various model compounds of different classes of light hydrocarbons on a mesoporous catalyst based on ZSM-5 zeolite
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The catalytic cracking performance of light hydrocarbon model compounds (1-hexene, n-octane, i-octane, ethylcyclohexane and ethylbenzene) over a mesoporous catalyst based on ZSM-5 zeolite was analyzed and compared using a microscale apparatus with a fixed-bed reactor. The effects of reaction temperature and weight hourly space velocity (WHSV) on feed conversion and the yields of ethene and propene were investigated. The results showed that with increased reaction temperature, the conversion of model compounds increased monotonically, and that of 1-hexene was close to 100% above 660°C; the yield of ethene plus propene of n-octane, i-octane and ethylcyclohexane increased continuously, while that of 1-hexene and ethylbenzene passed through maximum. With increased WHSV, the yield of ethene plus propene of ethylbenzene increased continuously, and that of the other model compounds decreased continuously. Through comprehensive analysis of the data, it is indicated that 1-hexene exhibited the highest cracking performance, followed by n-octane and ethylcyclohexane, whereas i-octane and ethylbenzene exhibited the lowest.
- Liu,Wang,Zhang,Liu,Liu,Meng
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p. 209 - 214
(2017/04/07)
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- Dimerization method for high activity and selectivity propylene
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The invention provides a dimerization method for high activity and selectivity propylene. The method includes the following steps that methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) is used as a catalyst promoter, and the propylene is subjected to a dimerization reaction under the catalytic action of an ethylidene bridged substituted diindene titanium group metal complex catalyst; and the ethylidene bridged substituted diindene titanium group metal complex catalyst is an internal compensation (meso-) ethylidene bridged substituted diindene titanium group metal complex catalyst or a racemization (rac-) ethylidene bridged substituted diindene titanium group metal complex catalyst. Compared with the prior art, the dimerization method provided by the invention is high in catalytic activity and high in dimerization selectivity, the rate can reach 99%, numerous follow-up operation steps in separation of products with the high degree of polymerization are omitted, the industrialization cost is reduced, and the industrial production needs can be met.
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Paragraph 0114; 0115; 0116; 0118-0121; 0124-0139; 0142-0153
(2017/06/02)
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- METHOD FOR PRODUCING FLUORINATED HYDROCARBON
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PROBLEM TO BE SOLVED: To provide a method for industrially advantageously producing a fluorinated hydrocarbon. SOLUTION: The method for producing a fluorinated hydrocarbon represented by formula (3) comprises bringing a secondary or tertiary ether compound represented by formula (1) into contact with an acid fluoride represented by formula (2) in the presence of a compound having an N-X bond (X is a halogen atom selected from a chlorine atom, a bromine atom, and an iodine atom) in a halogenated hydrocarbon-based solvent. (R1 and R2 are each independently a C1-C3 alkyl group; R3 is H, a methyl group, or an ethyl group; R4 and R5 are each a methyl group or an ethyl group; and R1 and R2 may be bonded together to form a ring structure.) SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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Paragraph 0063; 0067; 0072
(2018/03/09)
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- Synthesis of highly selective nano-structured functionalized SBA-15 metformin palladium composite catalyst in partial hydrogenation of alkynes
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In this research, a heterogeneous Nano-Structured functionalized SBA-15 metformin palladium composite catalyst is reported for the selective hydrogenation of alkynes. In the first place, A series of the heterogeneous mesoporous SBA-15 metformin palladium catalyst were prepared and afterwards the condition and the ratio of used materials were optimized to give rise a suitable high performance catalyst. The final nano-structured catalyst was characterized by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and served in partial hydrogenation of different alkynes, with high selectivity and high yield. The liquid phase hydrogenation was conducted under mild condition of room temperature and atmospheric pressure. The reactions were monitored every half an hour by gas chromatography and all of them were completed during 4-6 hours. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly confirmed the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over multiple cycles with a simple regeneration procedure.
- Kojoori, Reza Kia
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p. 3144 - 3149
(2016/11/18)
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- Partial hydrogenation of alkynes on highly selective nano-structured mesoporous silica MCM-41 composite catalyst
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In this research, we have developed a silica MCM-41/Metformin/Pd (II) nano composite catalyst for the selective hydrogenation of alkynes to the corresponding (Z)-alkenes under a mild condition of atmospheric pressure and room temperature. Firstly, functionalized Si-MCM-41 metformin catalyst with the optimum performance was prepared. Then, the synthesized catalyst was elucidated by X-ray powder diffraction, BET surface area, FT-IR spectrophotometer, Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and applied in partial hydrogenation of different alkynes, with high selectivity and high yield. The products were characterized by 1H-NMR, 13C-NMR, FT-IR, and Mass Spectrometry (MS) that strongly approved the (Z)-double bond configuration of produced alkenes. This prepared catalyst is competitive with the best palladium catalysts known for the selective liquid phase hydrogenation of alkynes and can be easily recovered and regenerated with keeping high activity and selectivity over at least three cycles with a simple regeneration procedure.
- Kojoori, Reza Kia
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p. 1121 - 1128
(2017/01/25)
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- PROCESS FOR DEHYDROGENATION OF ALKYL-CONTAINING COMPOUNDS USING MOLYBDENUM AND TUNGSTEN NITROSYL COMPLEXES
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A process for the dehydrogenation of alkyl-containing compounds comprises reacting an alkyl-containing compound and a Group VI nitrosyl complex characterized as a transition metal complex having the composition Cp'M(NO)(R1)(R2), wherein Cp' is selected from certain substituted and unsubstituted η5-cyclopentadienyl groups; M is W or Mo; and R1 and R2 are independently selected from CH2C(CH3)3; CH2Si(CH3)3; CH2(C6H5); CH3; hydrogen; and η3-allyl; provided that if R1 is hydrogen, R2 is η3-allyl; under conditions such that the alkyl-containing compound is converted to an olefin, and in particular embodiments, a terminal olefin. The dehydrogenation can be carried out using a neat and/or undried alkyl-containing compound and/or may be conducted under air, and does not require a sacrificial olefin to drive the reaction, thereby increasing convenience and decreasing cost in comparison with some other dehydrogenation processes.
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Page/Page column 11
(2016/08/10)
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- PROCESS FOR PRODUCING ALKANES USING MICROORGANISMS COMBINED WITH KOLBE SYNTHESIS
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The present invention relatesto a method of producing at least one alkane, the method comprising, -producing at least one carboxylic acid from a carbon source using a genetically modified microorganism, and -performing Kolbe electrolysis on the carboxylic acid to produce the alkane, wherein the alkane comprises at least 6 carbon atoms and the carboxylic acid comprises at least 4 carbon atomsand wherein the carbon source is selected from the group consisting of ethanol, acetate, propionate, butyrate, isobutyrate, valerate, hexanoate and combinations thereof and the microorganism is capable of producing the carboxylic acid using ethanol-carboxylate fermentation.
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Page/Page column 29
(2016/02/26)
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- Synthesis, structure and thermolysis of cis-dialkylplatinum(II) complexes - Experimental and theoretical perceptions
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The formation of new C-C bonds by metal complexes always stimulates great interest because these fundamental reaction types possess numerous potential applications in organic synthesis. These reactions are well documented for a variety of transition metal complexes. Herein we report synthesis and characterization of a series of platinum-dialkyl complexes (1-10) of the type [Pt(L2)R2], (where L2 = dppp (1,3-bis(diphenylphosphino)propane or L = PPh3; R = n-butyl to n-nonyl) with a view to understand the organic product distribution patterns on thermolysis. The single crystal X-ray structures of the complexes [Pt(dppp){CH2(CH2)3CH3}2] (1) and [Pt(dppp){CH2(CH2)6CH3}2] (7) are reported. Thermal decomposition studies of these complexes show interesting behaviour; the longer chain dialkyls i.e. C7-C9 complexes undergo reductive elimination whereas the shorter chain dialkyl complexes and C3-C6 prefer only the β-hydride elimination reaction. Possible mechanistic aspects are discussed. Theoretical calculations reveal the strongest delocalizations in both complexes involve the interaction of Pt-C bond pair electron density with the trans positioned Pt-P antibonding orbital and vice-versa.
- Venkatesh, Sadhana,Sravani, Chinduluri,Janardan, Sannapaneni,Suman, Pothini,Goud, E. Veerashekhara,Pavankumar,Leninkumar, Vardi,Bhat, Haamid R.,Sivaramakrishna, Akella,Vijayakrishna, Kari,Jha, Prakash C.,Smith, Gregory S.
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- Palladium-gold catalyst for the electrochemical reduction of CO2 to C1-C5 hydrocarbons
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Copper is a unique electrocatalyst for CO2 reduction, since it is one of the few catalysts able to produce methane, ethylene and ethane from CO2 with decent faradaic efficiencies. Here we report on the design and synthesis of a new non-copper-containing catalyst able to reduce CO2 to C1 to C5 hydrocarbons. This catalyst was designed by combining a metal that binds CO strongly, Pd, with a metal that binds CO weakly, Au, in an attempt to tune the binding energy of CO. We show that a mixture of C1-C5 hydrocarbons and soluble products are produced from an onset potential of -0.8 VRHE. We propose that the higher hydrocarbons are formed via a polymerization of -CH2 groups adsorbed on the catalyst surface.
- Kortlever,Peters,Balemans,Kas,Kwon,Mul,Koper
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supporting information
p. 10229 - 10232
(2016/08/23)
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- ALKANE DEHYDROGENATION PROCESS
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Disclosed herein are processes for dehydrogenation of an alkane to an alkene using an iridium pincer complex. In the dehydrogenation reactions, hydrogen that is co-formed during the process must be removed for the chemical reaction to proceed and to prevent the excess hydrogen from poisoning the catalyst. In one embodiment the process comprises providing an alkane feedstock comprising at least one alkane and contacting the alkane with an iridium pincer complex in the presence of a hydrogen acceptor selected from the group consisting of ethylene, propene, or mixtures to form an alkene product. The processes disclosed herein can accomplish facile, low-temperature transfer dehydrogenation of alkanes with unprecedented selectivities and TONs at a reasonable rate of conversion.
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Paragraph 0074
(2015/09/28)
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- CATALYST AND PROCESS FOR THE CO-DIMERIZATION OF ETHYLENE AND PROPYLENE
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Disclosed are novel catalyst solutions comprising an organic complex of nickel, an alkyl aluminum compound, a solvent, and a phosphine compound, that are useful for the preparation of butenes, pentenes and hexenes by the co-dimerization or cross-dimerization of ethylene and propylene. Also disclosed are processes for the dimerization of ethylene and propylene that utilize these catalyst solutions. The catalyst systems described herein demonstrate that, depending on the choice of phosphine compound used with the catalytically active nickel, it is indeed possible to lower the concentration of hexene olefins relative to butenes and pentenes, even in the presence of excess propylene. The selectivity to the linear or branched pentene product can also be controlled by the selection of the phosphine compound. The catalyst solutions may be used with mixtures of olefins.
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Paragraph 0088
(2015/03/28)
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- Dehydrogenation of n -Alkanes by Solid-Phase Molecular Pincer-Iridium Catalysts. High Yields of α-Olefin Product
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We report the transfer-dehydrogenation of gas-phase alkanes catalyzed by solid-phase, molecular, pincer-ligated iridium catalysts, using ethylene or propene as hydrogen acceptor. Iridium complexes of sterically unhindered pincer ligands such as iPr4PCP, in the solid phase, are found to give extremely high rates and turnover numbers for n-alkane dehydrogenation, and yields of terminal dehydrogenation product (α-olefin) that are much higher than those previously reported for solution-phase experiments. These results are explained by mechanistic studies and DFT calculations which jointly lead to the conclusion that olefin isomerization, which limits yields of α-olefin from pincer-Ir catalyzed alkane dehydrogenation, proceeds via two mechanistically distinct pathways in the case of (iPr4PCP)Ir. The more conventional pathway involves 2,1-insertion of the α-olefin into an Ir-H bond of (iPr4PCP)IrH2, followed by 3,2-β-H elimination. The use of ethylene as hydrogen acceptor, or high pressures of propene, precludes this pathway by rapid hydrogenation of these small olefins by the dihydride. The second isomerization pathway proceeds via α-olefin C-H addition to (pincer)Ir to give an allyl intermediate as was previously reported for (tBu4PCP)Ir. The improved understanding of the factors controlling rates and selectivity has led to solution-phase systems that afford improved yields of α-olefin, and provides a framework required for the future development of more active and selective catalytic systems. (Figure Presented).
- Kumar, Akshai,Zhou, Tian,Emge, Thomas J.,Mironov, Oleg,Saxton, Robert J.,Krogh-Jespersen, Karsten,Goldman, Alan S.
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p. 9894 - 9911
(2015/08/24)
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- New cofactor supports α,β-unsaturated acid decarboxylation via 1,3-dipolar cycloaddition
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The bacterial ubiD and ubiX or the homologous fungal fdc1 and pad1 genes have been implicated in the non-oxidative reversible decarboxylation of aromatic substrates, and play a pivotal role in bacterial ubiquinone (also known as coenzyme Q) biosynthesis or microbial biodegradation of aromatic compounds, respectively. Despite biochemical studies on individual gene products, the composition and cofactor requirement of the enzyme responsible for in vivo decarboxylase activity remained unclear. Here we show that Fdc1 is solely responsible for the reversible decarboxylase activity, and that it requires a new type of cofactor: a prenylated flavin synthesized by the associated UbiX/Pad1. Atomic resolution crystal structures reveal that two distinct isomers of the oxidized cofactor can be observed, an isoalloxazine N5-iminium adduct and a N5 secondary ketimine species with markedly altered ring structure, both having azomethine ylide character. Substrate binding positions the dipolarophile enoic acid group directly above the azomethine ylide group. The structure of a covalent inhibitor-cofactor adduct suggests that 1,3-dipolar cycloaddition chemistry supports reversible decarboxylation in these enzymes. Although 1,3-dipolar cycloaddition is commonly used in organic chemistry, we propose that this presents the first example, to our knowledge, of an enzymatic 1,3-dipolar cycloaddition reaction. Our model for Fdc1/UbiD catalysis offers new routes in alkene hydrocarbon production or aryl (de)carboxylation.
- Payne, Karl A. P.,White, Mark D.,Fisher, Karl,Khara, Basile,Bailey, Samuel S.,Parker, David,Rattray, Nicholas J.W.,Trivedi, Drupad K.,Goodacre, Royston,Beveridge, Rebecca,Barran, Perdita,Rigby, Stephen E. J.,Scrutton, Nigel S.,Hay, Sam,Leys, David
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supporting information
p. 497 - 501
(2015/07/02)
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- Solid-state molybdenum sulfide clusters with an octahedral metal framework as hydrogenation, dehydrogenation, and hydrogenolysis catalysts similar to the platinum group metals
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Solid-state molybdenum sulfide clusters with a nonstoichiometric sulfur-deficient site, CuxMo6S8-δ (x = 2.94 and δ ? 0.3) and Mo6S8-δ (δ ? 0.4), catalyze the dehydrogenation of cyclohexene, the hydrogenation of alkyne, alkene, aldehyde, ketone, and nitrobenzene, and the hydrogenolysis of halogenobenzenes in a hydrogen stream above 300 °C. This catalytic behavior of the clusters is similar to that of the platinum group metals, which is attributable to the isoelectronicity of sulfur-coordinating molybdenum atom to the platinum group metals.
- Kamiguchi, Satoshi,Arai, Kanako,Okumura, Kazu,Iida, Hajime,Nagashima, Sayoko,Chihara, Teiji
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p. 417 - 421
(2015/10/28)
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- From the lindlar catalyst to supported ligand-modified palladium nanoparticles: Selectivity patterns and accessibility constraints in the continuous-flow three-phase hydrogenation of acetylenic compounds
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Site modification and isolation through selective poisoning comprise an effective strategy to enhance the selectivity of palladium catalysts in the partial hydrogenation of triple bonds in acetylenic compounds. The recent emergence of supported hybrid materials matching the stereo- and chemoselectivity of the classical Lindlar catalyst holds promise to revolutionize palladium-catalyzed hydrogenations, and will benefit from an in-depth understanding of these new materials. In this work, we compare the performance of bare, lead-poisoned, and ligand-modified palladium catalysts in the hydrogenation of diverse alkynes. Catalytic tests, conducted in a continuous-flow three-phase reactor, coupled with theoretical calculations and characterization methods, enable elucidation of the structural origins of the observed selectivity patterns. Distinctions in the catalytic performance are correlated with the relative accessibility of the active site to the organic substrate, and with the adsorption configuration and strength, depending on the ensemble size and surface potentials. This explains the role of the ligand in the colloidally prepared catalysts in promoting superior performance in the hydrogenation of terminal and internal alkynes, and short-chain alkynols. In contrast, the greater accessibility of the active surface of the Pd-Pb alloy and the absence of polar groups are shown to be favorable in the conversion of alkynes containing long aliphatic chains and/or ketone groups. These findings provide detailed insights for the advanced design of supported nanostructured catalysts. Hybrid nanocatalysts: The classical Lindlar and the newly developed NanoSelectTM catalysts are confronted in the semi-hydrogenation of alkynes (see figure). Systematic testing under continuous-flow three-phase conditions, coupled with detailed characterization analyses and molecular simulations, enable the understanding of the structure of the catalysts and the associated activity and selectivity patterns for a wide range of acetylenic compounds.
- Vile, Gianvito,Almora-Barrios, Neyvis,Mitchell, Sharon,Lopez, Nuria,Perez-Ramirez, Javier
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p. 5926 - 5937
(2014/05/20)
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- Stereo- and chemoselective character of supported CEO2 catalysts for continuous-flow three-phase alkyne hydrogenation
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TiO2-, Al2O3-, and ZrO2- supported CeO2 catalysts with different Ce loadings were prepared by wet impregnation of the carriers with an acidified solution of cerium ammonium nitrate. The calcined catalysts were characterized by bulk and surface-sensitive techniques, which included microcalorimetry, and evaluated in the three-phase hydrogenation of alkynes under continuous-flow conditions at variable temperature (293-413 K) and pressure (1-90 bar). A number of acetylenic compounds, which contain terminal or internal triple bonds, conjugated unsaturations, and additional functionalities, were systematically assessed. The results revealed the full stereo- and chemoselective character of the ceria catalysts, which outperform the well-known Lindlar catalyst, and open promising perspectives for the revolutionary use of a cost-effective oxide for the production of olefinic compounds in the vitamin and fine chemical industries.
- Vile, Gianvito,Wrabetz, Sabine,Floryan, Leonard,Schuster, Manfred Erwin,Girgsdies, Frank,Teschner, Detre,Perez-Ramirez, Javier
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p. 1928 - 1934
(2014/08/05)
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- Kinetics and modelling of heptane steam-cracking
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The kinetics and product distribution during the cracking of heptane in the presence of steam were investigated. The experiments were performed in a flow reactor under atmospheric pressure in a temperature range of 680-760°C with a mass ratio of steam to heptane of 3: 1. The overall decomposition of heptane is represented by a first-order reaction with activation energy of 249.1 kJ mol-1 and a frequency factor of 3.13 × 1013 s-1. The reaction products were analysed using gas chromatography, the main product being ethylene. The molecular reaction scheme, which consists of a primary reaction and 24 secondary reactions between primary products, was used for modelling the experimental product yields. The yields of ethylene and hydrogen were in good agreement; however the experimental yields of propylene were higher than the predicted yields.
- Olahov, Natlia,Bajus, Martin,Hjekov, Elena,ugr, Luk,Marko, Jozef
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p. 1678 - 1689
(2015/03/30)
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- CATALYTIC DEHYDRATION OF ALCOHOLS AND ETHERS OVER A TERNARY MIXED OXIDE
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A ternary V—Ti—P mixed oxide is shown to catalytically dehydrate 2-methyl-tetrahydrofuran in high conversion to give piperylene, in good yield. Volatile products collected from this reaction contain piperylene in concentrations as high as 80 percent by weight. Dehydration of glycerol to acrolein in high conversion and moderate selectivity is also demonstrated. The catalyst is also shown to dehydrate other alcohols and ether substrates. The catalyst is resistant to deactivation and maintains activity between runs.
- -
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Paragraph 0038; 0046
(2013/03/28)
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- S-Acylation of aliphatic and aromatic thiols with carboxylic acids and their esters over solid acid catalysts in the gas phase at temperatures above 200 °c
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Benzenethiol is reacted with acetic acid in a hydrogen stream over [(Mo6Cl8)Cl4(H2O) 2]·6H2O. Catalytic activity of the clusters appears above 200 °C, yielding S-phenyl thioacetate. The selectivity is 98% at 300 °C. Niobium, tantalum, and tungsten halide clusters with the same octahedral metal framework also catalyze the reaction. Benzoic acid and aliphatic carboxylic acids afford the corresponding S-phenyl carbothioates by reaction with benzenethiol. Aliphatic thiols are also S-acylated to yield the corresponding S-alkyl carbothioates. When carboxylic esters are applied to the reaction with benzenethiol over [(Nb6Cl12)Cl 2(H2O)4]·4H2O at 450 °C, the sterically unhindered moiety of the ester is incorporated into the products: S-phenyl thioacetate or methyl phenyl sulfide is obtained selectively. A Br?nsted acid site developed on the cluster complex by thermal activation is the active site of the catalyst. Hence, solid acids such as silica-alumina, zeolites, and heteropoly acids that are stable above 200 °C also catalyze these reactions.
- Nagashima, Sayoko,Yamazaki, Hitomi,Kudo, Kentaro,Kamiguchi, Satoshi,Chihara, Teiji
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p. 332 - 338
(2013/07/26)
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- A highly selective route to linear alpha olefins from biomass-derived lactones and unsaturated acids
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This work demonstrates the use of Lewis-acid catalysts, such as gamma-alumina and tungstated alumina, for selective production of linear alpha olefins by decarboxylation of lactones and unsaturated carboxylic acids.
- Wang, Dong,Hakim, Sikander H.,Martin Alonso, David,Dumesic, James A.
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supporting information
p. 7040 - 7042
(2013/09/02)
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- ATP-independent formation of hydrocarbons catalyzed by isolated nitrogenase cofactors
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Reduce to produce: Molybdenum- and vanadium-nitrogenase cofactors have been isolated and shown to reduce carbon monoxide and cyanide ions to a mixture of alkanes and alkenes in the presence of a strong reductant, europium(II) diethylenetriaminepentaacetate (see scheme). Various hydrocarbons of up to seven carbon atoms in length are detected as products in these ATP-free reactions.
- Lee, Chi Chung,Hu, Yilin,Ribbe, Markus W.
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supporting information; experimental part
p. 1947 - 1949
(2012/04/04)
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- ATP-independent substrate reduction by nitrogenase P-cluster variant
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The P-cluster of nitrogenase is largely known for its function to mediate electron transfer to the active cofactor site during catalysis. Here, we show that a P-cluster variant (designated P*-cluster), which consists of paired [Fe4S4]-like clusters, can catalyze ATP-independent substrate reduction in the presence of a strong reductant, europium (II) diethylenetriaminepentaacetate [Eu(II)-DTPA]. The observation of a decrease of activity in the rank ΔnifH, ΔnifBΔnifZ, and ΔnifB MoFe protein, which corresponds to a decrease of the amount of P*-clusters in these cofactor-deficient proteins, firmly establishes P*-cluster as a catalytically active metal center in Eu(II)-DTPA-driven reactions. More excitingly, the fact that P*-cluster is not only capable of catalyzing the two-electron reduction of proton, acetylene, ethylene, and hydrazine, but also capable of reducing cyanide, carbon monoxide, and carbon dioxide to alkanes and alkenes, points to a possibility of developing biomimetic catalysts for hydrocarbon production under ambient conditions.
- Lee, Chi Chung,Hu, Yilin,Ribbe, Markus W.
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experimental part
p. 6922 - 6926
(2012/08/08)
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- Cross coupling reactions of multiple CCl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex
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The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6- diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp 3-sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20 min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4 mol% and turnover frequency (TOF) as high as 724 h-1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.
- Gartia, Yashraj,Nasini, Udaya Bhasker,Ghosh, Anindya,Biswas, Abhijit,Stadler, Matthew
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p. 322 - 327,6
(2020/07/30)
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- A novel iron complex for cross-coupling reactions of multiple C-Cl bonds in polychlorinated solvents with grignard reagents
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A novel iron(III) complex (2) of a pincer ligand [1, N2,N6-bis(2,6- diisopropylphenyl)pyridine-2,6-dicarboxamide] was developed and used for remediation of polychlorinated solvents via sp3-sp3 coupling of Grignard reagents with C-Cl bonds. The use of an iron catalyst for such coupling reactions is highly desirable due to its greener and more economical nature. Complex 2 was characterized using various spectroscopic techniques: electrospray ionization mass spectrometer (ESI-MS, m/z 575.1), cyclic voltammetry (E 1/2, 0.03 V and ΔE, 0.97 V), and ultraviolet visible (UV/Vis) spectroscopic techniques. The iron(III) complex showed efficient activation of multiple C-Cl bonds and catalyzing C-C coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents under ambient reaction conditions. Complex 2 showed exceptional activity with reactions approaching near completion in about 5 min. With the required catalyst loading as low as 0.2 mol%, considerably high turnover numbers (TON = 483) and turnover frequency (TOF = 5,800 h-1) were obtained. None of the products detected during the reaction contained any chlorine, indicating an efficient dechlorination method while synthesizing products of synthetic and commercial interest. Interestingly, the catalyst was capable of replacing all chlorine atoms in each polychlorinated solvent under the investigations with high conversion. Springer Science+Business Media, LLC 2012.
- Gartia, Yashraj,Pulla, Sharon,Ramidi, Punnamchandar,Farris, Carolina Costa,Nima, Zeid,Jones, Darin E.,Biris, Alexandru S.,Ghosh, Anindya
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p. 1397 - 1404
(2013/01/15)
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- The roles of carbide and hydride in oxide-supported palladium nanoparticles for alkyne hydrogenation
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Particle size affects the activity and selectivity to partial hydrogenation of 1-pentyne over oxide-supported palladium nanoparticles. Larger particles are intrinsically more selective because of the weaker bond strength of 1-pentene. In situ X-ray absorption near edge structure (XANES) at the Pd L3 edge revealed the formation of a carbide-like phase as soon as the catalyst is exposed to alkyne, irrespective of particle size. The newly formed phase prevented hydride formation. Surface poisoning of the palladium carbide by alkyne is responsible for the constantly high selectivity, up to almost complete conversion. At almost 100% conversion, all catalysts show low selectivity. The lack of significant pentyne adsorption on the surface causes pentene to undergo consecutive reactions, such as isomerization and complete hydrogenation. The structure of the catalyst was that of carbide-like phase and did not change. Palladium hydride did not form under any of the conditions. Exposure of a carbided catalyst to pure hydrogen leads to partial reversal of the structure. Hydride is not essential for complete hydrogenation to occur.
- Tew, Min Wei,Janousch, Markus,Huthwelker, Thomas,Van Bokhoven, Jeroen A.
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experimental part
p. 45 - 54
(2011/11/14)
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- Using modifiers to specify stereochemistry and enhance selectivity and activity in palladium-catalysed, liquid phase hydrogenation of alkynes
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Enhancing selectivity is a key parameter in green chemistry. In this study, we have examined the liquid phase hydrogenation of alkynes over a palladium catalyst and used modifiers to enhance selectivity and activity. The reactions studied were the hydrogenation of 1-pentyne and 2-pentyne. Five modifiers were used, pentane nitrile and its respective amine, pentyl amine, 3-phenyl propionitrile and its respective amine, 3-phenyl propylamine and trans-cinnamonitrile. These modifiers were not hydrogenated under reaction conditions. It was possible to obtain high (>90%) selectivities to 1-pentene and cis-2-pentene at high conversion. The effect on rate was dependent upon the modifier and the alkyne. The effect of the modifier was the same whether added with or before the reactants. Competitive reactions confirmed that terminal alkynes and internal alkynes are hydrogenated on separate sites and do not interfere and that the modifier influences each separately.
- Garcia, Paloma E.,Lynch, Ailsa S.,Monaghan, Andy,Jackson, S. David
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experimental part
p. 548 - 551
(2012/02/03)
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- Thermolysis studies on platinacycloalkane complexes
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Thermal decomposition studies on platinacycloalkanes of the type Pt(CH 2)mL2 (where m = 6,7,8,10 and L2 = dppp {1,3-bis(diphenylphosphino)propane}, dppe {1,2-bis(diphenylphosphino) ethane} or L = PPh3, tBu3P) are described. The results reveal that the organic product distribution depends on various factors such as the nature of ligand, the metal system, the mode of decomposition, the ring size and the temperature. Possible mechanistic pathways for the formation of various products are discussed. These platinacycloalkanes can be used as models for metallacycloalkane intermediates in catalytic reactions.
- Zheng, Feng,Sivaramakrishna, Akella,Moss, John R.
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scheme or table
p. 2457 - 2465
(2011/06/26)
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- Isolation of pure disubstituted e olefins through mo-catalyzed Z-selective ethenolysis of stereoisomeric mixtures
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Monoaryloxide-pyrrolide (MAP) complexes of molybdenum were employed for the selective ethenolysis of 1,2-disubstituted Z olefins in the presence of the corresponding E olefins. Reactions were performed in the presence of 0.02-3.0 mol % catalyst at 22 °C under 20 atm ethylene. We have demonstrated that the Z isomer of an easily accessible E:Z mixture can be destroyed through ethenolysis and the E alkene thereby isolated readily in high yield and exceptional stereoisomeric purity.
- Marinescu, Smaranda C.,Levine, Daniel S.,Zhao, Yu,Schrock, Richard R.,Hoveyda, Amir H.
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supporting information; experimental part
p. 11512 - 11514
(2011/09/16)
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- Co-metathesis of ethylene and olefinic compounds in ionic liquids
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Tungsten(VI) chloride dissolved in the ionic liquids is capable of catalyzing metathesis of 4-octene and co-metathesis of 4-penten-1-ol with ethylene; the latter reaction is preceded by double bond shift in the starting alkenol.
- Greish, Alexander A.,Kustov, Leonid M.,Vasnev, Alexander V.
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experimental part
p. 329 - 330
(2012/02/01)
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- Reactivity and kinetic-mechanistic studies of regioselective reactions of rhodium porphyrins with unactivated olefins in water that form β-hydroxyalkyl complexes and conversion to ketones and epoxides
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This article reports on the selective oxidation of unactivated alkenes to ketones and epoxides through the intermediacy of β-hydroxyalkyl rhodium porphyrin complexes which are formed by reactions of terminal alkenes with tetra(p-sulfonatophenyl)porphyrin
- Zhang, Jiadi,Wayland, Bradford B.,Yun, Lin,Li, Shan,Fu, Xuefeng
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supporting information; experimental part
p. 477 - 483
(2010/04/04)
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- Hydrogen storage using heterocyclic compounds: The hydrogenation of 2-methylthiophene
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Alkyl substituted thiophenes are promising candidates for hydrogen carriers, as their dehydrogenation reactions are known to occur under mild conditions. Four types of catalysts, including supported noble metals, bimetallic noble metals, transition metal
- Zhao,Oyama,Naeemi
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scheme or table
p. 172 - 184
(2010/11/05)
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