123-51-3Relevant articles and documents
Influence of Alkali Promoters in the Selective Hydrogenation of 3-Methyl-2-butenal over Ru/SiO2 Catalysts
Waghray, Akshay,Wang, Jian,Oukaci, Rachid,Blackmond, Donna G.
, p. 5954 - 5959 (1992)
The addition of potassium as a promoter to a Ru/SiO2 catalyst resulted in a striking shift in product selectivity in the hydrogenation of 3-methyl-2-butenal.The rate of hydrogenation at the C=O bond to produce the unsaturated alcohol increased concomitant with a decrease in the rate of C=C hydrogenation.IR spectroscopy showed a strong perturbation of the C=O bond for the alkali-promoted catalyst, and volumetric chemisorption and TPD results suggested that the alkali species blocked adsorption at low-coordination Ru sites.These adsorption and reaction studies suggest that polarization of the adsorbed substrate at the C=O bond is responsible for the significant shift in product selectivity upon alkali promotion.This work combines spectroscopic tools with the use of the catalytic reaction itself as a probe of catalyst surface chemistry.
Efficient and selective solvent-free homogeneous hydrogenation of aldehydes under mild reaction conditions using [RuCl2(dppb)(ampy)]
Angelini, Tommaso,Roseblade, Stephen,Zanotti-Gerosa, Antonio
, (2020)
The efficient, solvent-free homogeneous hydrogenation of aldehydes has been accomplished using the catalysts [RuCl2(dppb)(ampy)] and [RuCl2(dppf)(ampy)], providing high conversion to the corresponding alcohols at molar catalyst loadings of 10,000/1–50,000/1. A solvent-free protocol has been developed, allowing aldehydes to be efficiently reduced avoiding by-product formation and with minimal waste generation.[Formula presented]
Reactivity of 3-Methyl-Crotonaldehyde on Pt(111)
Birchem, T.,Pradier, C. M.,Berthier, Y.,Cordier, G.
, p. 503 - 510 (1994)
The reactivities of an α,β-unsaturated aldehyde, 3-methyl-crotonaldehyde, and of its two monohydrogenated products, 3-methyl-crotyl alcohol and 3-methyl-butyraldehyde have been investigated on a well-defined Pt(111) surface by low-pressure adsorption, thermal desorption, and high-pressure gas-phase hydrogenation experiments.Two kinetic regimes have been found when varying the 3-methyl-crotonaldehyde partial pressure and, in both cases, a rate-determining step has been proposed.At the origin of the reaction the high selectivity for 3-methyl-crotyl alcohol can be accounted for by the nature of the most abundant C5H9O isomer adsorbed species, the latter being determined by geometric effects.The influence of the 3-methyl-crotonaldehyde partial pressure on selectivities can be easily explained by a competitive hydrogenation between this molecule and the 3-methyl-crotyl alcohol.A similar previous study on Pt(111) has shown a quite different behaviour, and this work underlines the importance of the crystalline orientation of the platinum surface on the observed selectivities.
Hydrogenation of 3-methyl-crotonaldehyde on the Pt(553) stepped surface: Influence of the structure and of preadsorbed tin
Birchem,Pradier,Berthier,Cordier
, p. 68 - 77 (1996)
The hydrogenation of 3-methyl-crotonaldehyde was studied, in the gas phase, on a well-defined Pt(553) or Pt(S)-[5(111) × (111)] stepped surface and the results are compared with those of similar experiments on Pt(111). The selectivity is governed mainly by structural factors. Low-coordination step atoms create favorable hydrogenation sites for the production of saturated aldehyde, whereas (111) flat terraces lead to the formation of unsaturated alcohol. The influence of a preadsorbed submonolayer of tin was investigated on Pt(111) and Pt(553). The effect of this metallic additive depends on its local concentration and arrangement. Tin drastically changes the selectivity of Pt(553). At low coverage, tin, located in the vicinity of the steps, changes the selectivity to the benefit of the saturated alcohol. Al higher coverage (θ > 0.3), tin grows in islands on the terraces and the expected improvement in selectivity toward unsaturated alcohol was observed, suggesting a combination of electronic and geometric effects.
Photocatalytic Regeneration of Nicotinamide Cofactors by Quantum Dot-Enzyme Biohybrid Complexes
Brown, Katherine A.,Wilker, Molly B.,Boehm, Marko,Hamby, Hayden,Dukovic, Gordana,King, Paul W.
, p. 2201 - 2204 (2016)
We report the characterization of biohybrid complexes of CdSe quantum dots and ferredoxin NADP+-reductase for photocatalytic regeneration of NADPH. Illumination with visible light led to reduction of NADP+ to NADPH, with an apparent kcat of 1400 h-1. Regeneration of NADPH was coupled to reduction of aldehydes to alcohols catalyzed by a NADPH-dependent alcohol dehydrogenase, with each NADPH molecule recycled an average of 7.5 times. The quantum yield both of NADPH and alcohol production were 5-6% for both products. Light-driven NADPH regeneration was also demonstrated in a multienzyme system, showing the capacity of QD-FNR complexes to drive continuous NADPH-dependent transformations.
Cyclodextrins as first and second sphere ligands for Rh(I) complexes of lower-rim PTA derivatives for use as catalysts in aqueous phase hydrogenation
Potier, Jonathan,Guerriero, Antonella,Menuel, Stéphane,Monflier, Eric,Peruzzini, Maurizio,Hapiot, Frédéric,Gonsalvi, Luca
, p. 74 - 78 (2015)
The rhodium complex [Rh(cod)Cl(N-tBuBzPTA)]PF6 (2) was obtained by reacting the appropriate Rh(I) precursor with the lower-rim PTA derivative [N-tBuBzPTA]PF6 (tBuBz = 4-tert-butylbenzyl; PTA = 1,3,5-triaza-7-phosphaadamantane). The solubility and stability in water of 2 were increased in the presence of native-β-cyclodextrin (β-CD). The interaction of 2 with mono-amino β-cyclodextrin (β-CDNH2, 2 equiv.) led to a supramolecular Rh assembly (3), identified by 31P, 1H and 2D T-ROESY NMR experiments. The catalytic activity of 3 was evaluated in the water-phase hydrogenation of unsaturated and allylic alcohols and preliminary results are presented here.
Superior performance of a nanostructured platinum catalyst in water: Hydrogenations of alkenes, aldehydes and nitroaromatics
Maity, Prasenjit,Basu, Susmit,Bhaduri, Sumit,Lahiri, Goutam Kumar
, p. 1955 - 1962 (2007)
The hydrogenations of >C=CC=O and nitro groups in ArNO 2, with a water-soluble, polymer [poly(diallyldimethylammonium chloride)] supported, platinum carbonyl cluster {[Pt30(CO) 60]2-} derived catalyst 1, have been studied. The performance of 1 has been compared with that of two other platinum catalysts: catalyst 2 prepared by the hydrogen reduction of [PtCl6]2- supported on the same water-soluble polymer, and 3, a commercial platinum catalyst (5 % Pt on alumina). Our catalyst 1 has been found to be more active than 2 and 3, and by TEM it has been shown that the nanoparticles in 1 are much smaller than those in 2. In the hydrogenation of o-chloronitrobenzene both 1 and 2 were found to be more selective (no hydrodehalogenation) than 3. To evaluate the advantages of water as a solvent, comparative studies have been carried out in three different solvent systems: water, methanol and a 1:1 mixture of water and toluene. Hydrogenations in methanol have been found to be accompanied by induction times while no such induction time is observed in water. Both liquid (methyl pyruvate, benzaldehyde, safflower oil and styrene) and waterinsoluble solid nitroaromatics (o- and m-chloronitrobenzene and p-aminonitrobenzene) have been tested as substrates, and for all the substrates the activity in water was found to be higher.
Infrared Spectroscopic Studies of the Adsorption and Reaction of 3-Methyl-2-butenal over Alkali-Promoted Ru/SiO2 Catalysts
Waghray, Akshay,Blackmond, Donna G.
, p. 6002 - 6006 (1993)
Flow reaction studies of the hydrogenation of 3-methyl-2-butenal over Ru/SiO2 and potassium-promoted Ru/SiO2 were combined with in situ infrared spectroscopic monitoring of its adsorption and reaction as well as the adsorption of its reaction products.The presence of the alkali promoter significantly inhibited this hydrogenation to form the saturated aldehyde, a reaction which was followed by decarbonylation of the saturated aldehyde in a reverse migratory insertion process.The initial formation of adsorbed CO and hydrocarbon products from the saturated aldehyde may ultimately be responsible for the product distribution observed under steady-state reaction conditions.
Structural insights into the cofactor-assisted substrate recognition of yeast methylglyoxal/isovaleraldehyde reductase Gre2
Guo, Peng-Chao,Bao, Zhang-Zhi,Ma, Xiao-Xiao,Xia, Qingyou,Li, Wei-Fang
, p. 1486 - 1492 (2014)
Saccharomyces cerevisiae Gre2 (EC1.1.1.283) serves as a versatile enzyme that catalyzes the stereoselective reduction of a broad range of substrates including aliphatic and aromatic ketones, diketones, as well as aldehydes, using NADPH as the cofactor. Here we present the crystal structures of Gre2 from S. cerevisiae in an apo-form at 2.00 ? and NADPH-complexed form at 2.40 ? resolution. Gre2 forms a homodimer, each subunit of which contains an N-terminal Rossmann-fold domain and a variable C-terminal domain, which participates in substrate recognition. The induced fit upon binding to the cofactor NADPH makes the two domains shift toward each other, producing an interdomain cleft that better fits the substrate. Computational simulation combined with site-directed mutagenesis and enzymatic activity analysis enabled us to define a potential substrate-binding pocket that determines the stringent substrate stereoselectivity for catalysis.
METHOD FOR PRODUCING BIO ALCOHOL FROM INTERMEDIATE PRODUCTS OF ANAEROBIC DIGESTION TANK
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Paragraph 0057-0060; 0063; 0065-0066; 0068-0069; 0071, (2021/05/25)
The present invention relates to a method for producing a bio-alcohol by reacting a mixture of volatile fatty acid with methanol in 2 through 11 in a reactor in the presence of a 280 °C-membered alkaline earth metal catalyst or 400 °C transition metal catalyst formed based on a support.
