2808-76-6Relevant academic research and scientific papers
Effect of ketene additive and Si/Al ratio on the reaction of methanol over HZSM-5 catalysts
Hassanpour, Javad,Zamani, Mehdi,Dabbagh, Hossein A.
, (2018/03/01)
The influence of ketene as possible intermediate for the reaction of methanol to aromatics was investigated over HZSM-5 catalysts (Si/Al ratio of 15 and 9) using diketene-acetone (2,2,6-trimethyl-4H-1,3-dioxin-4-one) as ketene precursor under atmospheric
One-step hydroprocessing of fatty acids into renewable aromatic hydrocarbons over Ni/HZSM-5: Insights into the major reaction pathways
Xing, Shiyou,Lv, Pengmei,Wang, Jiayan,Fu, Junying,Fan, Pei,Yang, Lingmei,Yang, Gaixiu,Yuan, Zhenhong,Chen, Yong
, p. 2961 - 2973 (2017/02/05)
For high caloricity and stability in bio-aviation fuels, a certain content of aromatic hydrocarbons (AHCs, 8-25 wt%) is crucial. Fatty acids, obtained from waste or inedible oils, are a renewable and economic feedstock for AHC production. Considerable amounts of AHCs, up to 64.61 wt%, were produced through the one-step hydroprocessing of fatty acids over Ni/HZSM-5 catalysts. Hydrogenation, hydrocracking, and aromatization constituted the principal AHC formation processes. At a lower temperature, fatty acids were first hydrosaturated and then hydrodeoxygenated at metal sites to form long-chain hydrocarbons. Alternatively, the unsaturated fatty acids could be directly deoxygenated at acid sites without first being saturated. The long-chain hydrocarbons were cracked into gases such as ethane, propane, and C6-C8 olefins over the catalysts' Br?nsted acid sites; these underwent Diels-Alder reactions on the catalysts' Lewis acid sites to form AHCs. C6-C8 olefins were determined as critical intermediates for AHC formation. As the Ni content in the catalyst increased, the Br?nsted-acid site density was reduced due to coverage by the metal nanoparticles. Good performance was achieved with a loading of 10 wt% Ni, where the Ni nanoparticles exhibited a polyhedral morphology which exposed more active sites for aromatization.
Hydrogenation of arenes and N-heteroaromatic compounds over ruthenium nanoparticles on poly(4-vinylpyridine): A versatile catalyst operating by a substrate-dependent dual site mechanism
Fang, Minfeng,MacHalaba, Nataliya,Sanchez-Delgado, Roberto A.
experimental part, p. 10621 - 10632 (2011/11/29)
A nanostructured catalyst composed of Ru nanoparticles immobilized on poly(4-vinylpyridine) (PVPy) has been synthesized by NaBH4 reduction of RuCl3·3H2O in the presence of the polymer in methanol at room temperature. TEM measurements show well-dispersed Ru nanoparticles with an average diameter of 3.1 nm. Both powder XRD patterns and XPS data indicate that the Ru particles are predominantly in the zerovalent state. The new catalyst is efficient for the hydrogenation of a wide variety of aromatic hydrocarbons and N-heteroaromatic compounds representative of components of petroleum-derived fuels. The experimental data indicate the existence of two distinct active sites in the nanostructure that lead to two parallel hydrogenation pathways, one for simple aromatics involving conventional homolytic hydrogen splitting on Ru and a second one for N-heteroaromatics taking place via a novel heterolytic hydrogen activation on the catalyst surface, assisted by the basic pyridine groups of the support.
Ionic-liquid-like copolymer stabilized nanocatalysts in ionic liquids: II. Rhodium-catalyzed hydrogenation of arenes
Zhao, Chen,Wang, Han-zhi,Yan, Ning,Xiao, Chao-xian,Mu, Xin-dong,Dyson, Paul J.,Kou, Yuan
, p. 33 - 40 (2008/09/18)
Rhodium nanoparticles stabilized by the ionic-liquid-like copolymer poly[(N-vinyl-2-pyrrolidone)-co-(1-vinyl-3-butylimidazolium chloride)] were used to catalyze the hydrogenation of benzene and other arenes in ILs. The nanoparticle catalysts can endure forcing conditions (75 °C, 40 bar H2), resulting in high reaction rates and high conversions compared with other nanoparticles that operate in ILs. The hydrogenation of benzene attained record total turnovers of 20,000, and the products were easily separated without being contaminated by the catalysts. Other substrates, including alkyl-substituted arenes, phenol, 4-n-propylphenol, 4-methoxylphenol, and phenyl-methanol, were studied and in most cases were found to afford partially hydrogenated products in addition to cyclohexanes. In-depth investigations on reaction optimization, including characterization of copolymers, transmission electron microscopy, and an infrared spectroscopic study of nanocatalysts, were also undertaken.
Fused cycloalkyl amides and acids and their therapeutic applications
-
, (2008/06/13)
The present invention relates to the use of compounds of formula (I) for the treatment of epilepsy, bipolar disorder, psychiatric disorders, migraine, pain, or movement disorders, and to provide neuroprotection.
Fused cycloalkyl amides and acids and their therapeutic applications
-
, (2008/06/13)
The present invention relates to the use of compounds of formula (I) for the treatment of epilepsy, bipolar disorder, psychiatric disorders, migraine, pain, or movement disorders, and to provide neuroprotection.
Direct aromatic C-N bond cleavage evidenced in the hydrodenitrogenation of 2,6-dimethylaniline over cobalt-promoted Mo/Al2O3 sulfide catalysts: A reactivity and FT-IR study
Van Gestel,Dujardin,Mauge,Duchet
, p. 78 - 88 (2007/10/03)
The hydrodenitrogenation of 2,6-dimethylaniline (DMA) was studied over a series of sulfided Co(0-4.7%)-Mo(8.7%)/Al2O3 catalysts at 573 K under 4 MPa total pressure and 0-56 kPa H2S partial pressure. Two NiMo samples were tested for comparison. The reaction network presents three parallel routes: dearomatization of DMA followed by either hydrogenation-elimination to dimethylcyclohexenes and dimethylcyclohexanes, or NH3 elimination to mxylene, and disproportionation of DMA to 2-methylaniline and 2,4,6-trimethylaniline. We demonstrate that part of the xylene is formed by direct aromatic carbon-nitrogen bond cleavage through a nucleophilic substitution involving hydride species. On CoMo catalysts, in the presence of H2S, the amount of extra xylene is independent of Co content, while the dearomatization is promoted. Without H2S, this special substitution reaction is most important on the Mo catalyst, and strikingly Co acts as a poison. FT-IR spectroscopy of adsorbed carbon monoxide evidences a new type of sites on the sulfided catalysts after a mild hydrogen treatment. We propose that a site configuration located exclusively on unpromoted Mo atoms highly depleted in sulfur is responsible for the direct denitrogenation route. The NiMo couple behaves differently: xylene formation is independent of Ni content, which means that the specific Mo sites for direct C-N bond rupture are poisoned by nickel, even in the presence of H2S. The location of Co and Ni on the MoS2 slabs then appears different.
Stereochemistry of hydrodenitrogenation: The mechanism of elimination of the amino group from cyclohexylamines over sulfided Ni-Mo/γ-Al2O3 catalysts
Prins,Ranade,Rota,Ranade
, p. 389 - 399 (2007/10/03)
HDS and HDN are among the most significant catalytic processes in the petroleum industry, because during these processes sulfur and nitrogen are removed in the form of H2S and ammonia from oil fractions. The HDN of cyclohexylamine and of the diastereomers of 2-methylcyclohexylamine and 2,6-dimethylcyclohexylamine was studied at 200°-350°C and 50 bar over a sulfided Ni-Mo/γ-Al2O3 catalyst. The rate of HDN of alkyl-substituted cyclohexylamines over sulfided Ni-Mo catalysts depended on the number of β hydrogen atoms and on their stereochemical relation to the amino group. Isomerization of olefinic products and the amines prevented meaningful mechanistic studies at 350°C. The cis diastereomers reacted faster than the trans diastereomers, because they allowed for an anti geometric relationship in the chair conformation between the amino group and a hydrogen atom on a β carbon atom. The syn elimination occurred to a considerable extent at higher temperatures in molecules that were unable to undergo anti elimination. The activation energy of anti elimination was lower than that of syn elimination, and the activation energy of anti elimination involving a hydrogen atom attached to a tertiary β carbon atom was lower than that involving a hydrogen atom attached to secondary β carbon atom.
Competition of Mechanisms in Nucleophilic Substitution of Vinyl Halides. An Unequivocal Example of the Vinylic SRN1 Route
Galli, Carlo,Gentili, Patrizia,Rappoport, Zvi
, p. 6786 - 6795 (2007/10/02)
In a search for an unambiguous example of the vinylic SRN1 route, several vinyl bromides and iodides were reacted mostly with (-)CH2COCMe3, and sometimes with (-)CH2COPh, (-)CH(Me)COEt, and (EtO)2PO(-) ions, under Fe(2+)- or photostimulation in Me2SO.Vinyl halides having vinylic hydrogens, such as β-bromostyrene, gave acetylenic products, e.g., phenylacetylene or a tertiary PhCC-substituted alcohol, whereas vinyl halides with allylic hydrogens, such as Me2C=C(I)CHMe2, gave a substituted allene.Reduction products of the halogen, as well as substitution and rearranged substitution products, were also formed.The operation of ionic elimination-addition routes accounts for formation of most of the products, while the reduction products arise from an intermediate vinyl radical.Ph2C=C(Br)Ph (20) and Me2C=C(Br)Ph (25) gave both substitution and reduction products, but Me2C=C(Br)-t-Bu (23) gave only a reduction product.Formation of substitution products from the conjugated 20 and 25 was ascribed to a reaction via a vinylic SRN1 route, while lack of substitution in 23 is related to its nonconjugated system and to the consequent higher energy that the radical anion of the substitution product would have.The one here reported seems to be the first case of an exclusive genuine vinylic SRN1 process.
A Novel Intramolecular Cyclisation of Titanocene Vinylidene Complexes: Formation of Bicyclic Titanacyclo-butanes and -butenes
Dennehy, Robert D.,Whitby, Richard J.
, p. 1060 - 1062 (2007/10/02)
The intramolecular addition of a titanocene vinylidene complex formed by dechlorodimethylalumination of a 1-dimethylalumino-1-bis(η5-cyclopentadienyl)chlorotitano-alkene to an unactivated alkene or alkyne affords bicyclic titanacyclobutanes or titanacyclobutenes.
