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Catalyst Leads (catalyst + lead)
Selected AbstractsSynthesis of polyetherols with isocyanuric ring.INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2009Kinetics, mechanisms of reactions, part 2: Consecutive reaction of ethylene carbonate with isocyanuric acid The kinetics and mechanism of the reaction between isocyanuric acid and ethylene carbonate was studied. The multistep reaction in the presence of potassium carbonate as catalyst leads to polyetherols. The imide and hydroxyl groups of intermediates react with ethylene carbonate by slightly different mechanism and kinetics. The rate constants for these elementary processes were established, and based on these experimental data the mechanism of reaction was proposed. Using the isocyanuric acid and 1,3,5-tris(2-hydroxyethyl)isocyanurate, it has been found that the reaction of ethylene carbonate with intermediates occurs via a mixed mechanism. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 523,531, 2009 [source] Synthesis of (E)-3-Alkylidene-1-pyrrolines by the Rhodium- Catalyzed Cyclization of Terminal Alkynes with Homopropargylic AminesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009Yoshiya Fukumoto Abstract The cyclization of terminal alkynes with homopropargylic amines in the presence of a rhodium complex as catalyst leads to the formation of (E)-3-alkylidene-1-pyrrolines. The reaction tolerates a wide range of functional groups on the terminal alkynes. The formation of a vinylidene-rhodium complex, followed by the intermolecular nucleophilic attack of a homopropargylic amine nitrogen on the ,-carbon atom of the vinylidene-rhodium complex, is proposed as a key step in the catalytic reaction. [source] Synthesis of thiazolo[3,2- d][1,2,4] triazines through palladium-catalyzed heteroannulation of acetylenic compoundsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2007Majid M. Heravia The reaction of 6-methyl-5-(prop-2-ynylthio)-5,6-dihydro-1,2,4-triazin-3(4H)-one 1 with various iodobenzenes 2 in the presence of palladium catalyst leads to the formation of substituted triazolotriazines. [source] Simultaneous Catalytic Removal of Nitrogen Oxides and Soot from Diesel Exhaust Gas over Potassium Modified Iron OxideCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2003S. Kureti Abstract Iron oxide modified by potassium, i.e. Fe1.9K0.1O3, exhibits high catalytic performance for the simultaneous conversion of soot and NOx into CO2 and N2. The present study shows that long-time treatment of the catalyst leads to a drastic decrease in the activity, whereas even the aged catalyst maintains considerable activity. On the other hand, long-time treatment causes selective N2 formation, i.e. no more formation of the byproduct N2O. This alteration of catalytic performance is likely due to agglomeration of the promoter potassium being present at the surface of catalyst. Detailed experiments were carried out with a more realistic diesel model exhaust gas to confirm that Fe1.9K0.1O3 is a suitable catalyst for the simultaneous removal of soot and NOx between 350 and 480 °C. It was assumed that (CO) intermediates, formed by the catalytic reaction of NOx and oxygen with the soot surface, are the reactive species in NOx -soot conversion. [source] Rhodium-Catalyzed Allylation of Aldehydes with Homoallylic Alcohols by Retroallylation and Isomerization to Saturated Ketones with Conventional or Microwave HeatingCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2008Yuto Sumida Abstract The treatment of an aldehyde with a tertiary homoallylic alcohol at 100,250,°C in the presence of cesium carbonate and a rhodium catalyst leads to allyl transfer from the homoallylic alcohol to the aldehyde. The process includes Rh-mediated retroallylation to form an allyl rhodium species as the key intermediate. The homoallylic alcohol formed initially through allyl transfer is converted under the reaction conditions into the corresponding saturated ketone when bulky ligands are used. Microwave heating at 250,°C accelerates the reaction significantly. [source] Oxidation of 1,4-Dioxane over Ti-MWW in the Presence of H2O2CHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 3 2008Weibin Fan Dr. Ti time for dioxane: Oxidation of 1,4-dioxane with aqueous H2O2 over various titanosilicates was investigated. Use of Ti-MWW as catalyst leads to much higher conversions than with TS-1 and Ti-Beta under solvent-free conditions and is accounted for by a radical mechanism. The number of active intermediate Ti species is highly dependent on the substrate, solvent, and titanosilicate used. [source] High Power Density Electric Double Layer Capacitor with Improved Activated CarbonCHINESE JOURNAL OF CHEMISTRY, Issue 2 2003Yang Hui Abstract The improvement on commercial activated carbon (AC) through the reactivation under steam in the presence of NiCl2 catalyst leads to the increases of both energy and power densities of electric double layer (dl) capacitors. When AC was treated at 875 °C for 1 h, its discharge specific capacitance increases up to 53.67 F· g,1, an increase of about 25% compared to the as-received AC. Moreover, a significant increase in high rate capability of electric dl capacitor was found after the improvements. Surprisingly, both the treated and untreated AC samples showed similar specific surface area and pore size distribution, but some changes in the surface groups and their concentrations after reactivation were verified by X-photoelectron spectra. Thus, it is reasonable to conclude that the decrease in the surface concentration of the carbonyl-containing species for the improved AC results in an increase of accessibility of the pores to the organic electrolyte ion, causing the enhancements of both the specific capacitance and high rate capability. [source] Electrospray mass spectrometry studies of macromolecules containing 1,3-oxazolidine moietiesRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2004J. Ma, ska-Solich The polycondensation of terephthalaldehyde with 2-amino-2-methyl-1,3-propanediol using acidic catalysts leads to the formation of linear polymers and macrocyclic compounds with 2-(1,,4,-phenylene)-5-methyl-1-aza-3,7-dioxabicyclo[3.3.0]octane as the repeating unit in all compounds. The structure of the polymer was determined by 1H- and 13C-NMR spectroscopy, and electrospray ionization mass spectrometric (ESI-MS) analysis. ESI-MS measurements were used to study the details of the polymer structure and support the equimolar alternating nature of bicyclo- O,N -acetals of terephthaldehyde in these macromolecules. Copyright © 2004 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||