Search results for "Methacrolein"
showing 10 items of 11 documents
Reaction products and pathways in the selective oxidation of C-2-C-4 alkanes on MoVTeNb mixed oxide catalysts
2010
[EN] The catalytic properties of MoVTeNbO catalysts during the selective oxidation of short chain alkanes and olefins (C-2-C-4) have been comparatively studied The main reaction products have been ethylene from ethane acrylic acid from propane maim anhydride from n-butane and methacrolein from isobutane FTIR studies of the adsorption of the main reaction products i e olefins and aldehydes over MoVTeNbO catalyst has been carried out Accordingly the reaction pathway is explained on the basis of the characteristics of the alkane fed the stability and reactivity of both the intermediates and the reaction products and the nature of the catalytic sites involved in each reaction (C) 2010 Elsevier …
Methyl vinyl ketone+OH and methacrolein+OH oxidation reactions: a master equation analysis of the pressure- and temperature-dependent rate constants.
2006
High-level electronic structure calculations and master equation analyses were carried out to obtain the pressure- and temperature-dependent rate constants of the methyl vinyl ketone+OH and methacrolein+OH reactions. The balance between the OH addition reactions at the high-pressure limit, the OH addition reactions in the fall-off region, and the pressure-independent hydrogen abstractions involved in these multiwell and multichannel systems, has been shown to be crucial to understand the pressure and temperature dependence of each global reaction. In particular, the fall-off region of the OH addition reactions contributes to the inverse temperature dependence of the rate constants in the Ar…
Enthalpies of formation of isoprene’s major oxidation byproducts
2005
Abstract The theoretical enthalpies of formation ( Δ f H 298 . 15 ∘ ) of methyl vinyl ketone (MVK, CH 2 CHC(O)CH 3 ), methacrolein (MACR, CH 2 C(CH 3 )CHO), and the radical products formed in their corresponding OH radical oxidations have been calculated with DFT (MPW1K/6-31+G(d,p)) and multilevel (MCCM-UT-CCSD(T)//MPW1K/6-31+G(d,p)) methods. The bond dissociation energies ( BDE , DH 298 . 15 0 ) of the H-atoms that can be abstracted from the MVK and MACR molecules, and the C–O forming bonds of the OH addition products are also calculated. The regioselectivity of the global reaction is discussed in terms of bond strength.
Selective oxidative activation of isobutane on a novel vanadium-substituted bimodal mesoporous oxide V-UVM-7
2006
Abstract New vanado-silicates with a bimodal mesoporous system (V-UVM-7) and high vanadium contents (Si/V ≥ 7) have been prepared by a modification of the so-called atrane method. Its morphology consists of aggregation of nano-particles with V-MCM-41 structure, creating a second broader porous system in their interparticle space. Its structure allows to incorporate a high V contents into tetrahedral sites of the framework while keeping vanadium dispersion. V-UVM-7 catalysts are very active and selective for the direct transformation of isobutane to isobutene and methacrolein. Total conversion and methacrolein-to-isobutene ratio in the products increased with increasing vanadium contents. Th…
Mukaiyama–Michael Reactions with Acrolein and Methacrolein: A Catalytic Enantioselective Synthesis of the C17–C28 Fragment of Pectenotoxins
2013
Enantioselective iminium-catalyzed reactions with acrolein and methacrolein are rare. A catalytic enantioselective Mukaiyama-Michael reaction that readily accepts acrolein or methacrolein as substrates, affording the products in good yields and 91-97% ee, is presented. As an application of the methodology, an enantioselective route to the key C17-C28 segment of the pectenotoxin using the Mukaiyama-Michael reaction as the key step is described.
Direct oxidation of isobutane to methacrolein over V-MCM-41 catalysts
2004
High vanadium content mesoporous vanado-silicates with MCM-41-like structure, obtained by the atrane route, catalyse the direct oxidation of isobutane to methacrolein with 30% selectivity, and a total dehydrogenation (olefin plus methacrolein) selectivity up to 74%.
Die radikalinduzierte polymerisation von acrolein und α-methylacrolein in dimethylformamid. Polymere acroleine. 22. Mitt.1
1962
Die Polymerisation von Acrolein in Dimethylformamid (DMF) bei 40 und 50°C mit wechselnden Mengen Azodiisobuttersaurenitril wird beschrieben. Bei Umsatzen uber 16% tritt unter diesen Bedingungen Gelbildung ein. Methacrolein wurde mit verschiedenen Katalysatoren in DMF polymerisiert. Die Polymerisate bleiben bis zu hohen Umsatzen in Losung. Die Bruttoaktivierungsenergie ergibt sich zu 21 kcal/Mol. Die Bruttogeschwindigkeit als Funktion der Monomeren-Konzentration und der Konzentration von Azodiisobuttersaurenitril last sich bei 50°C durch folgende Gleichung beschreiben: The polymerization of acrolein in DMF at 40 and 50°C. in presence of varying amounts of azodiisobutyronitrile was investigat…
Pressure dependence in the methyl vinyl ketone + OH and methacrolein + OH oxidation reactions: an electronic structure study.
2005
High-level electronic structure calculations were carried out for the study of the reaction pathways in the OH-initiated oxidations of methyl vinyl ketone (MVK) and methacrolein (MACR). For the two conformers of MVK (called synperiplanar and antiperiplanar), the addition channels of OH to the terminal and central carbon atom of the double bond dominate the overall rate constant, whereas the abstraction of the methyl hydrogen atoms has no significant kinetic role. In the case of MACR, only the antiperiplanar conformer is important in its reactivity. In addition, the lower Gibbs free energy barrier for MACR corresponds to the aldehydic hydrogen abstraction reaction, which will be somewhat mor…
Über Segmentlängenverteilung und Lichtabsorption bei Copolymeren aus Methacrylnitril und Acrolein oder Methacrolein. Polymere Acroleine. 31. Mitt.
1964
Copolymere aus Methacrylnitril und Acrolein oder Methacrolein werden hinsichtlich der Absorption der Carbonylgruppe im Ultravioletten und Infraroten untersucht. Zur Beschreibung des Absorptionsverhaltens wird die statistische Theorie von ALFREY und GOLDFINGER uber die Segmentlangenverteilung in copolymeren benutzt. Es ergibt sich, das im wesentlichen die isoliert stehenden Aldehydgrundbausteine einen Beitrag zur Carbonyl-absorption liefern. Bei Sequenzen aus zwei und drei Aldehydgrundbausteinen reagieren die Carbonylgruppen zu cyclischen Aldehydhydratathern, wahrend bei langeren Sequenzen ungefahr 20% der Carbonylgruppen nicht cyclisieren. Copolymers from methacrylnitrile and acrolein or me…
Über die copolymerisation des acroleins und des methacroleins in homogener lösung. Polymere acroleine. 25. Mitt.
1962
Die Copolymerisation des Acroleins und des Methacroleins in Dimethylformamid sowie in Dioxan wird beschrieben. Die Parameter folgender Systeme wurden bestimmt: Acrolein/Acrylnitril (r1 = 1,60; r2 = 0,52); Acrolein/Acrylamid (r1 = 1,69; r2 = 0,21); Acrolein/Methacrylnitril (r1 = 0,72; r2 = 1,20); Acrolein/2-Vinylpyridin (r1 = 4; r2 = 0) und Methacrolein/Methacrylnitril (r1 = 1,78; r2 = 0,40). Die Berechnung der Q-und e-Werte bzw. der q- und ϵ-Werte ergab fur Acrolein: Q = 0,64; e = 0,61; q = -2,8 kcal/Mol; ϵ = 0,19 = 10−10 elektrostatische Einheiten und fur Methacrolein: Q = 1,59; e = 0,36; q = −3,4 kcal/Mol; ϵ = 0,11 = 10−10 elektrostatische Einheiten. The copolymerisation of acrolein and m…