- Influence of Alkali Promoters in the Selective Hydrogenation of 3-Methyl-2-butenal over Ru/SiO2 Catalysts
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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.
- Waghray, Akshay,Wang, Jian,Oukaci, Rachid,Blackmond, Donna G.
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- Efficient and selective solvent-free homogeneous hydrogenation of aldehydes under mild reaction conditions using [RuCl2(dppb)(ampy)]
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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]
- Angelini, Tommaso,Roseblade, Stephen,Zanotti-Gerosa, Antonio
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- Reactivity of 3-Methyl-Crotonaldehyde on Pt(111)
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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.
- Birchem, T.,Pradier, C. M.,Berthier, Y.,Cordier, G.
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- Hydrogenation of 3-methyl-crotonaldehyde on the Pt(553) stepped surface: Influence of the structure and of preadsorbed tin
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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.
- Birchem,Pradier,Berthier,Cordier
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- Photocatalytic Regeneration of Nicotinamide Cofactors by Quantum Dot-Enzyme Biohybrid Complexes
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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.
- Brown, Katherine A.,Wilker, Molly B.,Boehm, Marko,Hamby, Hayden,Dukovic, Gordana,King, Paul W.
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- Cyclodextrins as first and second sphere ligands for Rh(I) complexes of lower-rim PTA derivatives for use as catalysts in aqueous phase hydrogenation
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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.
- Potier, Jonathan,Guerriero, Antonella,Menuel, Stéphane,Monflier, Eric,Peruzzini, Maurizio,Hapiot, Frédéric,Gonsalvi, Luca
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- Superior performance of a nanostructured platinum catalyst in water: Hydrogenations of alkenes, aldehydes and nitroaromatics
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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.
- Maity, Prasenjit,Basu, Susmit,Bhaduri, Sumit,Lahiri, Goutam Kumar
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- Infrared Spectroscopic Studies of the Adsorption and Reaction of 3-Methyl-2-butenal over Alkali-Promoted Ru/SiO2 Catalysts
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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.
- Waghray, Akshay,Blackmond, Donna G.
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- Structural insights into the cofactor-assisted substrate recognition of yeast methylglyoxal/isovaleraldehyde reductase Gre2
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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.
- Guo, Peng-Chao,Bao, Zhang-Zhi,Ma, Xiao-Xiao,Xia, Qingyou,Li, Wei-Fang
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- MANUFACTURING METHOD OF PENTYL ALCOHOL
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A method for preparing methyl butenoic acid using (A) acetone is provided to economically mass-produce a pentyl alcohol economically. Reducing a (B)-methyl butenoic acid with a reducing agent. The present invention relates to a method for producing a pentyl alcohol comprising.
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Paragraph 0068; 0070; 0072-0075
(2021/08/05)
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- METHOD FOR PRODUCING BIO ALCOHOL FROM INTERMEDIATE PRODUCTS OF ANAEROBIC DIGESTION TANK
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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.
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Paragraph 0043-0048
(2021/05/25)
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- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Method for recycling byproducts in synthesis of diphenyl sulfide compound
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The invention provides a method for recycling byproducts in synthesis of a diphenyl sulfide compound. The byproducts comprise alkyl alcohol and dimethyl disulfide. The method comprises the steps of (1) mixing the byproducts in synthesis of the diphenyl sulfide compound with a sodium nitrite aqueous solution, adding concentrated hydrochloric acid for reaction, and obtaining alkyl nitrite and dimethyl disulfide; and (2) mixing the products obtained in the step (1) with copper powder, adding an aniline compound for reaction, carrying out desolvation treatment on the obtained reaction solution toobtain a diphenyl sulfide compound and byproducts, and returning the byproducts to the step (1). According to the recycling method, the byproducts do not need to be separated, the byproducts serve asraw materials to be directly applied to synthesis of the diphenyl sulfide compound, the process steps are simple and safe, cyclic utilization of the materials is achieved, and the raw material cost ofindustrial production of the diphenyl sulfide compound and the treatment cost of industrial three wastes are remarkably reduced.
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Paragraph 0115; 0121-0123
(2021/03/30)
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- Metal complex catalysts and method for catalytically reducing carboxylic acids
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The invention relates to a metal complex catalyst, which contains at least one of metal complexes with a chemical formula comprising a structural unit represented by a formula I. According to the invention, the center metal of the metal complex catalyst is iridium, and the metal complex catalyst is composed of pentamethylcyclopentadienyl, a bitetrahydropyrimidine ligand and proper coordination anions; the metal complex catalyst has activity on a carboxylic acid reduction reaction, and a carboxylic acid compound is reduced into an alcohol compound in the presence of hydrogen; and the method ismild in reaction condition, can be carried out at room temperature, and is good in catalytic performance and high in reduction product yield.
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Paragraph 0085-0144; 0151; 0152; 0167; 0168; 0178-0179
(2020/06/20)
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- Validated HPLC and stability-indicating densitometric chromatographic methods for simultaneous determination of camylofin dihydrochloride and paracetamol in their binary mixture
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Two accurate, sensitive, precise and selective HPLC and stability-indicating TLC methods were developed for the simultaneous determination of camylofin-2HCl and paracetamol. Forced acid, alkali and oxidative degradation of camylofin-2HCl?were tried where complete degradation was achieved using 5?N HCl. HPLC method was developed to determine the mixture of the two drugs using Zorbax NH2 column and a mobile phase of 0.5percent triethylamine and pH 3.0 adjusted with 0.1percent phosphoric acid and methanol (70:30 v/v) over concentration ranges of 3–90 and 10–95?μg/mL for camylofin-2HCl and paracetamol, respectively.TLC method was used for the separation of camylofin from its acid degradate and paracetamol using chloroform–methanol–acetone–conc. ammonia (8:2:2:0.1, by volume) as developing system and band scanning at 254 nm over concentration ranges of 5–40?μg/band for camylofin-2HCl and 0.1–0.5?μg/band for paracetamol. The validation of two methods was carried out according to ICH guideline. Accuracy ranged between 98.47 and 100.67percent for the two methods with acceptable precision RSDpercent ranging between 0.66 and 1.47percent.
- Abdel Razeq, Sawsan A.,Khalil, Israa A.,Mohammd, Samah A.
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p. 2587 - 2597
(2020/06/17)
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- Pd catalysts supported on dual-pore monolithic silica beads for chemoselective hydrogenation under batch and flow reaction conditions
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Two different types of palladium catalysts supported on dual-pore monolithic silica beads [5% Pd/SM and 0.25% Pd/SM(sc)] for chemoselective hydrogenation were developed. Alkyne, alkene, azide, and nitro functionalities and the aromatic N-Cbz protecting group were chemoselectively hydrogenated using 5% Pd/SM. On the other hand, 0.25% Pd/SM(sc) showed unique and higher hydrogenation catalyst activity toward a wide variety of reducible functionalities. Furthermore, the catalyst activities of both 5% Pd/SM and 0.25% Pd/SM(sc) under flow hydrogenation conditions were also evaluated. A pre-packed 5% Pd/SM cartridge could be used continuously for at least 72 h without any loss of catalyst activity. The 0.2% Pd/SM(sc) catalyst prepacked in a cartridge showed high catalyst activity for the flow hydrogenation of trisubstituted alkenes under mild reaction conditions. This journal is
- Yamada, Tsuyoshi,Ogawa, Aya,Masuda, Hayato,Teranishi, Wataru,Fujii, Akiko,Park, Kwihwan,Ashikari, Yosuke,Tomiyasu, Noriyuki,Ichikawa, Tomohiro,Miyamoto, Riichi,Bai, Hongzhi,Matsuyama, Kiyoshi,Nagaki, Aiichiro,Sajiki, Hironao
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p. 6359 - 6367
(2020/11/03)
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- An On-Demand, Selective Hydrogenation Catalysis over Pt?Fe Nanocatalysts under Ambient Condition
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The selective hydrogenation of organic compounds with multiple unsaturated bonds is of significant for fine chemicals, while simultaneously achieving high selectivities of different potential products is still great challenge. Herein, we have successfully designed a nanocatalysis system, which can serve as a control switch of selective α, β-unsaturated aldehydes hydrogenation towards potential products in a highly on-demand fashion. We demonstrate that the PtFe nanospheres (NSs) represent excellent selectivity (>92.8 %) to unsaturated alcohols with high conversion (>99.7 %), due to the higher electron density of the active Pt atoms. When introducing AlCl3, the selectivity of saturated aldehydes enhances to 97.1 % at 95.8 % conversion, owing to synergy between PtFe NSs and AlCl3. Finally, the PtFe?A NSs generated by etching away the Fe can promote the selectivity saturated alcohols (>99.7 %) with the highest activity, on account of more exposed active sites after the chemical etching. Significantly, the developed nanocatalysis system can also exhibit high activity/selectivity for other typical α, β-unsaturated aldehydes as well as excellent stability after consecutive reactions. This work provides a guideline for the rational design highly active and selective Pt-based nanocatalyst.
- Yang, Chengyong,Bai, Shuxing,Feng, Yonggang,Huang, Xiaoqing
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p. 2265 - 2269
(2019/04/13)
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- The Low Dimensional Co-Based Nanorods as a Novel Platform for Selective Hydrogenation of Cinnamaldehyde
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Abstract: Since hydrogenation of C=C bond in the cinnamaldehyde is thermodynamically favored, the selective hydrogenation of C=O group is challenging. Developing effective catalysts for this transformation has been hindered by the intrinsic disadvantages of traditional materials for decades. Hereby, we report the synthesis of the low dimensional Co based nanorods (NRs) as the effective platform for C=O groups hydrogenation in the conjugated compounds. The Pt/Co-NRs catalyst is simply fabricated by loading the Pt nano-particles (NPs) on the Co-NRs and the stability of the Co-NRs support is improved by coordination between the Pt NPs and the pyridinic N ring. Resorting to XRD, FT-IR, XPS, HRTEM, DTG-TG characterization methods, the catalytic mechanism for C=O bond hydrogenation has been proposed. The synergistic effects of K+ and OH? enhance the polarization of C=O group, leading to more adsorption of C=O groups on the Co-NRs so as to promote its hydrogenation performance. In the absence of spatial micropores in low dimensional Co based nanorods, the Pt/Co-NRs catalyst is more advantageous for mass transfer. Under optimal conditions, the conversion of cinnamaldehyde is 97.9% with 92.7% selectivity of cinnamyl alcohol within 3 h. In addition, the selectivity of cinnamyl alcohol changes slightly (only 2.4% fluctuations) after five recycle tests. Graphical Abstract: [Figure not available: see fulltext.].
- Yuan, Tao,Liu, Derong,Gu, Jianshan,Xia, Yongde,Pan, Yue,Xiong, Wei
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p. 2906 - 2915
(2019/04/30)
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- Preparation of a Series of Supported Nonsymmetrical PNP-Pincer Ligands and the Application in Ester Hydrogenation
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In contrast to their symmetrical analogues, nonsymmetrical PNP-type ligand motifs have been less investigated despite the modular pincer structure. However, the introduction of mixed phosphorus donor moieties provides access to a larger variety of PNP ligands. Herein, a facile solid-phase synthesis approach towards a diverse PNP-pincer ligand library of 14 members is reported. Contrary to often challenging workup procedures in solution-phase, only simple workup steps are required. The corresponding supported ruthenium-PNP catalysts are screened in ester hydrogenation. Usually, industrially applied heterogeneous catalysts require harsh conditions in this reaction (250–350 °C at 100–200 bar) often leading to reduced selectivities. Heterogenized reusable Ru-PNP catalysts are capable of reducing esters and lactones selectively under mild conditions.
- Konrath, Robert,Spannenberg, Anke,Kamer, Paul C. J.
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supporting information
p. 15341 - 15350
(2019/11/14)
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- Aerobic Oxidation of Secondary Alcohols with Nitric Acid and Iron(III) Chloride as Catalysts in Fluorinated Alcohol
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Fluorinated alcohols as solvents strongly influence and direct chemical reaction through donation of strong hydrogen bonds while being weak acceptors. We used 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the activating solvent for a nitric acid and FeCl3-catalyzed aerobic oxidation of secondary alcohols to ketones. Reaction proceeded selectively with excellent yields with no reaction on the primary alcohol group. Oxidation of benzyl alcohols proceeds selectively to aldehydes with only HNO3 as the catalyst, while reaction on tertiary alcohols proceeds through dehydration and dimerization. A mechanistic study showed in situ formation of NOCl that converts alcohol into alkyl nitrite, which in the presence of Fe3+ ions and fluorinated alcohol decomposes into ketone. The study indicates that iron(III) acts also as the single-electron transfer catalyst in regeneration of NOCl reactive species.
- Mo?ina, ?tefan,Iskra, Jernej
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p. 14579 - 14586
(2019/11/14)
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- Multicomponent Pt-Based Zigzag Nanowires as Selectivity Controllers for Selective Hydrogenation Reactions
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The selective hydrogenation of α, β-unsaturated aldehyde is an extremely important transformation, while developing efficient catalysts with desirable selectivity to highly value-added products is challenging, mainly due to the coexistence of two conjugated unsaturated functional groups. Herein, we report that a series of Pt-based zigzag nanowires (ZNWs) can be adopted as selectivity controllers for α, β-unsaturated aldehyde hydrogenation, where the excellent unsaturated alcohol (UOL) selectivity (>95%) and high saturated aldehyde (SA) selectivity (>94%) are achieved on PtFe ZNWs and PtFeNi ZNWs+AlCl3, respectively. The excellent UOL selectivity of PtFe ZNWs is attributed to the lower electron density of the surface Pt atoms, while the high SA selectivity of PtFeNi ZNWs+AlCl3 is due to synergy between PtFeNi ZNWs and AlCl3, highlighting the importance of Pt-based NWs with precisely controlled surface and composition for catalysis and beyond.
- Bai, Shuxing,Bu, Lingzheng,Shao, Qi,Zhu, Xing,Huang, Xiaoqing
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supporting information
p. 8384 - 8387
(2018/06/29)
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- Hydrogen Sulfide: A Reagent for pH-Driven Bioinspired 1,2-Diol Mono-deoxygenation and Carbonyl Reduction in Water
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Hydrogen sulfide (H2S) was evaluated for its peculiar sulfur radical species generated at different pHs and was used under photolytical conditions in aqueous medium for the reduction of 1,2-diols to alcohols. The conversion steps of 1,2-cyclopentanediol to cyclopentanol via cyclopentanone were analyzed, and it was proven that the reaction proceeds via a dual catalytic/radical chain mechanism. This approach was successfully adapted to the reduction of a variety of carbonyl compounds using H2S at pH 9 in water. This work opens up the field of environmental friendly synthetic processes using the pH-driven modulation of reactivity of this simple reagent in water.
- Barata-Vallejo, Sebastián,Ferreri, Carla,Golding, Bernard T.,Chatgilialoglu, Chryssostomos
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supporting information
p. 4290 - 4294
(2018/07/29)
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- Efficient hydroboration of carbonyls by an iron(II) amide catalyst
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An easily prepared iron(ii) amide precatalyst enables the selective hydroboration of carbonyls with HBpin (pinacolborane) in the absence of any additive. The reactions proceed with low catalytic loading (1-3 mol%) under mild reaction conditions and display wide functional group compatibility. Aldehydes are selectively hydroborated in the presence of other reducible functional groups, such as ketones, alkenes, nitriles, esters, amides, acids and halides.
- Baishya, Ashim,Baruah, Swavalina,Geetharani
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p. 9231 - 9236
(2018/07/29)
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- Hydrosilylation of Aldehydes and Formates Using a Dimeric Manganese Precatalyst
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The formally zero-valent Mn dimer [(Ph2PEtPDI)Mn]2 has been synthesized upon reducing (Ph2PEtPDI)MnCl2 with excess Na/Hg. Single crystal X-ray diffraction analysis has revealed that [(Ph2PEtPDI)Mn]2 possesses a η4-PDI chelate about each Mn center, as well as η2-imine coordination across the dimer. The chelate metrical parameters suggest single electron PDI reduction and EPR spectroscopic analysis afforded a signal consistent with two weakly interacting S = 1/2 Mn centers. At ambient temperature in the absence of solvent, [(Ph2PEtPDI)Mn]2 has been found to catalyze the hydrosilylation of aldehydes at loadings as low as 0.005 mol % (0.01 mol % relative to Mn) with a maximum turnover frequency of 9,900 min-1 (4,950 min-1 per Mn). Moreover, the [(Ph2PEtPDI)Mn]2-catalyzed dihydrosilylation of formates has been found to proceed with turnover frequencies of up to 330 min-1 (165 min-1 relative to Mn). These metrics are comparable to those described for the leading Mn catalyst for this transformation, the propylene-bridged variant (Ph2PPrPDI)Mn; however, [(Ph2PEtPDI)Mn]2 is more easily inhibited by donor functionalities. Carbonyl and carboxylate hydrosilylation is believed to proceed through a modified Ojima mechanism following dimer dissociation.
- Mukhopadhyay, Tufan K.,Ghosh, Chandrani,Flores, Marco,Groy, Thomas L.,Trovitch, Ryan J.
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p. 3477 - 3483
(2017/10/03)
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- Mechanistic Investigation of Bis(imino)pyridine Manganese Catalyzed Carbonyl and Carboxylate Hydrosilylation
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We recently reported a bis(imino)pyridine (or pyridine diimine, PDI) manganese precatalyst, (Ph2PPrPDI)Mn (1), that is active for the hydrosilylation of ketones and dihydrosilylation of esters. In this contribution, we reveal an expanded scope for 1-mediated hydrosilylation and propose two different mechanisms through which catalysis is achieved. Aldehyde hydrosilylation turnover frequencies (TOFs) of up to 4900 min-1 have been realized, the highest reported for first row metal-catalyzed carbonyl hydrosilylation. Additionally, 1 has been shown to mediate formate dihydrosilylation with leading TOFs of up to 330 min-1. Under stoichiometric and catalytic conditions, addition of PhSiH3 to (Ph2PPrPDI)Mn was found to result in partial conversion to a new diamagnetic hydride compound. Independent preparation of (Ph2PPrPDI)MnH (2) was achieved upon adding NaEt3BH to (Ph2PPrPDI)MnCl2 and single-crystal X-ray diffraction analysis revealed this complex to possess a capped trigonal bipyramidal solid-state geometry. When 2,2,2-trifluoroacetophenone was added to 1, radical transfer yielded (Ph2PPrPDI·)Mn(OC·(Ph)(CF3)) (3), which undergoes intermolecular C-C bond formation to produce the respective Mn(II) dimer, [(μ-O,Npy-4-OC(CF3)(Ph)-4-H-Ph2PPrPDI)Mn]2 (4). Upon finding 3 to be inefficient and 4 to be inactive, kinetic trials were conducted to elucidate the mechanisms of 1- and 2-mediated hydrosilylation. Varying the concentration of 1, substrate, and PhSiH3 revealed a first order dependence on each reagent. Furthermore, a kinetic isotope effect (KIE) of 2.2 ± 0.1 was observed for 1-catalyzed hydrosilylation of diisopropyl ketone, while a KIE of 4.2 ± 0.6 was determined using 2, suggesting 1 and 2 operate through different mechanisms. Although kinetic trials reveal 1 to be the more active precatalyst for carbonyl hydrosilylation, a concurrent 2-mediated pathway is more efficient for carboxylate hydrosilylation. Considering these observations, 1-catalyzed hydrosilylation is believed to proceed through a modified Ojima mechanism, while 2-mediated hydrosilylation occurs via insertion.
- Mukhopadhyay, Tufan K.,Rock, Christopher L.,Hong, Mannkyu,Ashley, Daniel C.,Groy, Thomas L.,Baik, Mu-Hyun,Trovitch, Ryan J.
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p. 4901 - 4915
(2017/04/11)
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- PRODUCTION OF 2-SUBSTITUTED 4-METHYL-TETRAHYDROPYRANS FROM STARTING MATERIALS CONTAINING 2-ALKYL-4,4-DIMETHYL-1,3-DIOXANES
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The invention relates to a method for producing 2-substituted 4-methyltetrahydropyrans of general formula (I) from starting materials containing at least one 2-substituted 4,4-dimethyl-1,3-dioxane of general formula (II).
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Paragraph 0257; 0261
(2017/04/13)
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- A synthetic pantenate isopentene aldehyde selective hydrogenation method (by machine translation)
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The invention discloses a isopentene aldehyde pantenate selective hydrogenation synthesis method, comprises a batch charging; nitrogen, hydrogen replacement; hydrogenation reaction; the separating step. The use of the raw material is 1 copy of the isopentene aldehyde, 0.1 - 10 parts of water and 0.02 - 0.2 a catalyst, the catalyst used is of the VIII group metal water-soluble salt and water-soluble ligand to form a water-soluble complex. The synthesis reaction of the conversion rate and the isopentene aldehyde pantenate high selectivity; catalyst aqueous phase can realize the 20 or more times of the recycled, catalyst unit consumption low, greatly reduces the production cost, and is suitable for industrial production. (by machine translation)
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Paragraph 0040; 0041; 0042; 0043; 0044; 0045-0082
(2017/10/11)
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- Indium-mediated cleavage of the trityl group from protected alcohols and diols
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The reaction of primary, secondary, allylic and benzylic trityl ethers with indium powder in MeOH/NH4Cl led to reductive cleavage of the trityl-oxygen bond, affording the corresponding alcohols in good to excellent yield under very mild reaction conditions. The detritylation process could successfully be extended to mono and detritylated diols. This methodology represents a new and efficient detritylation procedure under mild reaction conditions.
- Behloul, Cherif,Chouti, Aicha,Guijarro, David,Foubelo, Francisco,Nájera, Carmen,Yus, Miguel
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p. 7937 - 7941
(2016/11/19)
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- Conjugated polymeric metal porphyrin for catalytic oxidation of alkanes and cycloalkanes method
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The invention discloses a method for catalyzing air or oxygen to oxidize alkane and cycloparaffin by use of conjugated polymetalloporphyrin. Solid polymetalloporphyrin which has high porosity and specific surface area and is formed by coupling and polymerizing conjugated alkynyl is used as a catalyst for catalytic oxidation of hydrocarbon bonds of the alkane and the cycloparaffin under a gentle condition so as to obtain a corresponding oxidation product such as ketonic acid and the like. The amount of the used catalyst is small, and the catalytic effect is good. The catalyst is not dissolved or decomposed in a reaction system and can be recycled for lots of times. The transformation rate of the hydrocarbon bonds in catalytic oxidation is high and good alcohol ketone selectivity is achieved.
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Paragraph 0022; 0023
(2017/02/09)
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- Hydrogenation of allyl alcohols catalyzed by aqueous palladium and platinum nanoparticles
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A series of Pd and Pt nanoparticles (NPs) was prepared starting from the corresponding metal ions and lignosulphonates; NPs were tested as catalysts for allyl alcohols hydrogenation in water at room temperature and pressure. All NPs were active with sharp differences in conversions and selectivities: Pt NPs formed mainly saturated alcohols, whereas Pd NPS were more active, but less selective, forming, in addition to saturated alcohols, also isomeric unsaturated alcohols and aldehydes, both saturated and unsaturated.
- Di Pietrantonio, Krystel,Coccia, Francesca,Tonucci, Lucia,D'Alessandro, Nicola,Bressan, Mario
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p. 68493 - 68499
(2015/09/01)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- A method of manufacturing a tertiary amine
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PROBLEM TO BE SOLVED: To provide a method for producing a tertiary amine selectively with a high yield by a reductive amination reaction in a batch system. SOLUTION: In this method for producing the tertiary amine, an aldehyde expressed by formula R-CHO (in the formula, R shows a 2-20C aliphatic hydrocarbon group, 3-20C alicyclic hydrocarbon group or 6-20C aromatic hydrocarbon group), ammonia and hydrogen are reacted together in a batch system in the presence of a hydrogenation catalyst, to thereby produce the tertiary amine expressed by formula (R-CH2)3N (in the formula, R is defined above), wherein a palladium catalyst is used as the hydrogenation catalyst, and the reaction is performed under the condition of a hydrogen pressure of 0.1-6.5 MPa. COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0025; 0027; 0030
(2016/12/16)
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- Cobalt-Catalyzed Hydrogenation of Esters to Alcohols: Unexpected Reactivity Trend Indicates Ester Enolate Intermediacy
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The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts, with few exceptions. Presented here is the first cobalt-catalyzed hydrogenation of esters to the corresponding alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates. Getting involved: The atom-efficient and environmentally benign catalytic hydrogenation of carboxylic acid esters to alcohols has been accomplished in recent years mainly with precious-metal-based catalysts. Presented here is the first cobalt-catalyzed hydrogenation of esters to alcohols. Unexpectedly, the evidence indicates the unprecedented involvement of ester enolate intermediates.
- Srimani, Dipankar,Mukherjee, Arup,Goldberg, Alexander F. G.,Leitus, Gregory,Diskin-Posner, Yael,Shimon, Linda J. W.,Ben David, Yehoshoa,Milstein, David
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supporting information
p. 12357 - 12360
(2015/10/12)
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- Efficient one-pot production of 1,2-propanediol and ethylene glycol from microalgae (Chlorococcum sp.) in water
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The catalytic valorization of microalgae, a sustainable feedstock to alleviate dependence on fossil fuel and offset greenhouse gases emissions, is of great significance for production of biofuels and value-added chemicals from aquatic plants. Here, an interesting catalytic process is reported to convert microalgae (Chlorococcum sp.) into 1,2-propanediol (1,2-PDO) and ethylene glycol (EG) in water over nickel-based catalysts. The influences of reaction temperature, initial H2 pressure and reaction time on the product distribution were systematically investigated by using a batch reactor. Under optimal reaction conditions (at 250 °C for 3 h with 6.0 MPa of H2 pressure), microalgae were directly and efficiently converted over a Ni-MgO-ZnO catalyst and the total yield of polyols was up to 41.5%. The excellent catalytic activity was attributed to the smaller size and better dispersion of Ni particles on the MgO-ZnO supporter based on the characterization results as well as its tolerance to nitrogen-containing compounds. Besides, the reaction pathway was proposed based on the formation of reaction intermediates and the results of model compound conversion.
- Miao,Zhu,Wang,Tan,Wang,Liu,Kong,Sun
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p. 2538 - 2544
(2015/04/22)
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- Selective aldehyde reduction in ketoaldehydes with NaBH4-Na 2CO3-H2O at room temperatures
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A variety of aliphatic and aromatic ketoaldehydes were reduced to the corresponding ketoalcohols with a mixture of sodium borohydride (1.2 equivalents) and sodium carbonate (sixfold molar excess) in water. Reactions were performed at room temperatures(typically) 2 h, and yields of isolated products generally ranged from 70% to 85%. A bis-carbonate-borane complex, [(BH3)2CO2]2- 2Na+, possibly formed from the reagent mixture, is likely the active reductant. The moderated reactivity of this acylborane species would explain the chemoselectivity observed in the reactions. The readily available reagents and the mild aqueous conditions make for ease of operation and environmental compatibility, and make a useful addition to available methodology. Copyright
- Chandrasekhar, Sosale,Shrinidhi, Annadka
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supporting information
p. 2051 - 2056
(2014/07/07)
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- Expanding ester biosynthesis in Escherichia coli
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To expand the capabilities of whole-cell biocatalysis, we have engineered Escherichia coli to produce various esters. The alcohol O-acyltransferase (ATF) class of enzyme uses acyl-CoA units for ester formation. The release of free CoA upon esterification with an alcohol provides the free energy to facilitate ester formation. The diversity of CoA molecules found in nature in combination with various alcohol biosynthetic pathways allows for the biosynthesis of a multitude of esters. Small to medium volatile esters have extensive applications in the flavor, fragrance, cosmetic, solvent, paint and coating industries. The present work enables the production of these compounds by designing several ester pathways in E. coli. The engineered pathways generated acetate esters of ethyl, propyl, isobutyl, 2-methyl-1-butyl, 3-methyl-1-butyl and 2-phenylethyl alcohols. In particular, we achieved high-level production of isobutyl acetate from glucose (17.2 g l -1). This strategy was expanded to realize pathways for tetradecyl acetate and several isobutyrate esters.
- Rodriguez, Gabriel M,Tashiro, Yohei,Atsumi, Shota
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p. 259 - 265
(2014/04/03)
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- Highly regioselective nickel-catalyzed cross-coupling of N -tosylaziridines and alkylzinc reagents
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Herein, we report the first ligand-controlled, nickel-catalyzed cross-coupling of aliphatic N-tosylaziridines with aliphatic organozinc reagents. The reaction protocol displays complete regioselectivity for reaction at the less hindered C-N bond, and the products are furnished in good to excellent yield for a broad selection of substrates. Moreover, we have developed an air-stable nickel(II) chloride/ligand precatalyst that can be handled and stored outside a glovebox. In addition to increasing the activity of this catalyst system, this also greatly improves the practicality of this reaction, as the use of the very air-sensitive Ni(cod)2 is avoided. Finally, mechanistic investigations, including deuterium-labeling studies, show that the reaction proceeds with overall inversion of configuration at the terminal position of the aziridine by way of aziridine ring opening by Ni (inversion), transmetalation (retention), and reductive elimination (retention).
- Jensen, Kim L.,Standley, Eric A.,Jamison, Timothy F.
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supporting information
p. 11145 - 11152
(2014/08/18)
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- Synthesis of pyrrole N-derivatives from oxazolidines
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Transformations of oxazolidine derivatives synthesized from industrially produced amino alcohols, aldehydes, and ketones under basic or acidic catalysis lead to the formation of N-alkyl- and N-(hydroxyalkyl)-substituted pyrroles in 19-81% yields.
- Sadykov, E. Kh.,Stankevich,Lobanova,Klimenko
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p. 219 - 224
(2014/04/17)
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- Novel Ether Linked Compounds and Improved Treatments for Cardiac and Cardiovascular Disease
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A compound of Formula (I), and its pharmaceutically acceptable salt or salts and physiologically hydrolysable derivatives in free form or salt form: wherein R1 is independently selected from F, Cl, Br, CN, NH2, OH, CHO, COOH, oxo, C1-4alkyl, C1-4alkoxy, CONH2 (optionally mono- or di-substituted by C1-4alkyl) and SO2NH2, R2 is independently selected from C1-6allkyl substituted by R3 wherein the C1-6alkyl chain optionally comprises one or two heteroatoms select from O; R3 is selected from aryl, C3-6cycloalkyl, C3-6heterocyclyl and C3-6heteroaryl, wherein the heterocyclyl and heteroaryl rings are nitrogen containing; and wherein R3 is optonally substituted by one or more groups selected from R1; n1 is zero or an integer from 1 to 2; n2 is an integer from 1 to 2; and the sum of n1 and 2 is less than or equal to 2; R5 is selected from any group defined for R1 and R2; R6a and R6b are independently selected from H or C1-4alkyl; R7 is independently selected from F, Cl, Br, CN, NH2, OH, CHO, COOH, oxo, C1-4alkyl, C1-4alkoxy, CONH2 (optionally mono- or di-substituted by C1-4alkyl) and SO2NH2, Q1, Q2 and Q3 are independently selected from H or any group defined for R1 and R2; or Q1 and Q2 or Q2 and Q3 together form a C5-6heteroaryl or C5-6heterocylclic ring; optionally containing one or two heteroatoms selected from N and O optionally substituted by any group selected from R5; Z is selected from linear C2-3 alkylene; X3 is O; X4 is selected from aryl, a 9-10 membered heteroaryl ring or a 9-10 membered heterocyclic ring, wherein the heteroaryl and heterocyclic rings contain one or more heteroatoms selected from N, and optionally additionally O, and wherein X4 is optionally substituted by one or two oxo moieties and is optionally substituted by one or more groups selected from R7; with the proviso that (i) when X4 is phenyl then Q1 and Q2 or Q2 and Q3—together form an optionally substituted heteroaryl or heterocylclic ring as defined above; and (ii) when Q1, Q2 and Q3 are independently selected from H or any group defined for R1 and R2 then X4 is not phenyl except when R2 is C1-5alkyl substituted by R3 wherein R3 is C3-6heterocyclyl as defined above, their preparation and novel intermediates, compositions thereof and their use in the prevention or treatment of cardiac and cardiovascular disease and methods for the treatment thereof.
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Page/Page column
(2014/04/17)
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- Control of metal catalyst selectivity through specific noncovalent molecular interactions
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The specificity of chemical reactions conducted over solid catalysts can potentially be improved by utilizing noncovalent interactions to direct reactant binding geometry. Here we apply thiolate self-assembled monolayers (SAMs) with an appropriate structure to Pt/Al2O3 catalysts to selectively orient the reactant molecule cinnamaldehyde in a configuration associated with hydrogenation to the desired product cinnamyl alcohol. While nonspecific effects on the surface active site were shown to generally enhance selectivity, specific aromatic stacking interactions between the phenyl ring of cinnamaldehyde and phenylated SAMs allowed tuning of reaction selectivity without compromising the rate of desired product formation. Infrared spectroscopy showed that increased selectivity was a result of favorable orientation of the reactant on the catalyst surface. In contrast, hydrogenation of an unsaturated aldehyde without a phenyl ring showed a nontunable improvement in selectivity, indicating that thiol SAMs can improve reaction selectivity through a combination of nonspecific surface effects and ligand-specific near-surface effects.
- Kahsar, Karl R.,Schwartz, Daniel K.,Medlin, J. Will
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p. 520 - 526
(2014/01/23)
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- Bis(phosphine)cobalt dialkyl complexes for directed catalytic alkene hydrogenation
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Planar, low-spin cobalt(II) dialkyl complexes bearing bidentate phosphine ligands, (P - P)Co-(CH2SiMe3)2, are active for the hydrogenation of geminal and 1,2-disubstituted alkenes. Hydrogenation of more hindered internal and endocyclic trisubstituted alkenes was achieved through hydroxyl group activation, an approach that also enables directed hydrogenations to yield contrasteric isomers of cyclic alkanes.
- Friedfeld, Max R.,Margulieux, Grant W.,Schaefer, Brian A.,Chirik, Paul J.
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supporting information
p. 13178 - 13181
(2015/03/30)
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- Process for preparing 3-substituted 2-alkenals, in particular prenal
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The present invention to a process for preparing 2-alkenals of the formula I in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C10-aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl ; comprising dehydrogenating an alkenol of the formula II, an alkenol of the formula III or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol II or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
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- PROCESS FOR PREPARING 3-SUBSTITUTED 2-ALKENALS, IN PARTICULAR PRENAL
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The present invention to a process for preparing 2-alkenals of the formula (I) in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C-10 aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl; comprising dehydrogenating an alkenol of the formula (II), an alkenol of the formula (III) or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol III or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
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- Chemoselective hydrogenation of the olefinic bonds using a palladium/magnesium-lanthanum mixed oxide catalyst
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A palladium/magnesium-lanthanum mixed oxide catalyst is found to be an efficient heterogeneous catalyst for the chemoselective hydrogenation of olefinic double bonds in the presence of various functional groups. The catalyst was recovered by centrifugation and reused for several cycles with consistent activity and selectivity. Copyright
- Kantam, Mannepalli Lakshmi,Kishore, Ramineni,Yadav, Jagjit,Sudhakar, Medak,Venugopal, Akula
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supporting information; experimental part
p. 663 - 669
(2012/04/23)
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- Poly(vinyl)chloride supported palladium nanoparticles: Catalyst for rapid hydrogenation reactions
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Palladium nanoparticles supported over poly(vinyl)chloride matrix (PVC-Pd0) are prepared through an efficient and inexpensive protocol. The catalyst has been characterized by XRD, SEM and TEM and its utility for the reduction of a range of functional groups as well as for the removal of some common protecting groups employed in peptide chemistry is demonstrated.
- Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
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experimental part
p. 2597 - 2601
(2011/05/12)
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- Modified grape seed oils
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Edible oils are described which are extracted from dried fermented grape seeds isolated from a fermented grape pomace that has undergone fermentation, e.g., primary fermentation during wine making. The edible oils contain distinguishing flavor and fragrance chemicals evidenced by organoleptic evaluation and chemical analysis, in which these chemicals are substantially lacking in grape seed oils that have been similarly extracted from grape seeds isolated from non-fermented grape pomace.
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Paragraph 0084
(2011/05/14)
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- Catalytic isomerization of allyl alcohols to carbonyl compounds using poisoned Pd nanoparticles
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This article shows that Pd nanoparticles (NPs) poisoned by alkanethiolate monolayers can catalyze the isomerization of allyl alcohols to the corresponding carbonyl compounds in a relatively high efficiency and with a high selectivity. Pd nanoparticles are produced by the borohydride reduction of K 2PdCl4 in toluene/H2O using sodium S-dodecylthiosulfate as a source for the alkanethiolate ligands. Both kinetic and thermodynamic effects control the catalytic reactions of various substituted allyl alcohols. In general, less substituted allyl alcohols including prop-2-en-1-ol and pent-1-en-3-ol are isomerized to the corresponding aldehyde or ketone more efficiently. More substituted allyl alcohols such as but-2-en-1-ol and 3-methylbut-2-en-1-ol do not undergo isomerization under the same condition. However, the presence of reactive, less substituted allyl alcohols is found to promote the isomerization of poorly reactive, more substituted allyl alcohols.
- Sadeghmoghaddam, Elham,Ga?eb, Khalil,Shon, Young-Seok
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experimental part
p. 137 - 141
(2012/02/02)
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- Highly efficient and stereoselective biosynthesis of (2S,5S)-hexanediol with a dehydrogenase from Saccharomyces cerevisiae
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The enantiopure (2S,5S)-hexanediol serves as a versatile building block for the production of various fine chemicals and pharmaceuticals. For industrial and commercial scale, the diol is currently obtained through bakers' yeast-mediated reduction of 2,5-hexanedione. However, this process suffers from its insufficient space-time yield of about 4 g L-1 d-1 (2S,5S)-hexanediol. Thus, a new synthesis route is required that allows for higher volumetric productivity. For this reason, the enzyme which is responsible for 2,5-hexanedione reduction in bakers' yeast was identified after purification to homogeneity and subsequent MALDI-TOF mass spectroscopy analysis. As a result, the dehydrogenase Gre2p was shown to be responsible for the majority of the diketone reduction, by comparison to a Gre2p deletion strain lacking activity towards 2,5-hexanedione. Bioreduction using the recombinant enzyme afforded the (2S,5S)-hexanediol with >99% conversion yield and in >99.9% de and ee. Moreover, the diol was obtained with an unsurpassed high volumetric productivity of 70 g L-1 d-1 (2S,5S)-hexanediol. Michaelis-Menten kinetic studies have shown that Gre2p is capable of catalysing both the reduction of 2,5-hexanedione as well as the oxidation of (2S,5S)-hexanediol, but the catalytic efficiency of the reduction is three times higher. Furthermore, the enzyme's ability to reduce other keto-compounds, including further diketones, was studied, revealing that the application can be extended to α-diketones and aldehydes.
- Mueller, Marion,Katzberg, Michael,Bertau, Martin,Hummel, Werner
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experimental part
p. 1540 - 1550
(2010/07/04)
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- PROCESS AND APPARATUS FOR THE PRODUCTION OF ALCOHOLS
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A process utilising the gases carbon monoxide, carbon dioxide and hydrogen to produce alcohols directly, comprises the steps of bringing a fluid mixture comprising carbon monoxide, carbon dioxide and hydrogen into contact with the surfaces of a supported tubular porous catalyst membrane having a range of pore sizes including micropores, mesopores and macropores, controlling the temperature of the said catalyst membrane, maintaining a pressure over said catalyst membrane of from 88 to 600 kPa, and recovering alcohol containing product formed by contact of the fluid mixture with said catalyst membrane.
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Page/Page column 4
(2010/09/05)
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- POLYOL ETHERS AND PROCESS FOR MAKING THEM
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New polyol ether compounds and a process for their preparation. The process comprises reacting a polyol, a carbonyl compound, and hydrogen in the presence of hydrogenation catalyst, to provide the polyol ether. The molar ratio of polyol to carbonyl compound in the process is greater than 5:1.
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Page/Page column 9
(2010/03/31)
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- Ionic liquid immobilized nickel(0) nanoparticles as stable and highly efficient catalysts for selective hydrogenation in the aqueous phase
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Nickel nanoparticles (NPs) well-dispersed in the aqueous phase were conveniently prepared by reducing nickel(II) salt with hydrazine in the presence of the functionalized ionic liquid 1-(3-aminopropyl)-2,3-dimethylimidazolium bromide. UV/Vis spectros-copy, elemental analysis, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS) show the presence of a weak interaction of the functionalized ionic liquid with Ni11 and Ni 0 complexes. The face-centered cubic structure of the Ni0 NPs was confirmed by X-ray diffraction (XRD) characterization. Transmission electron microscopy (TEM) images reveal that smaller Ni0 particles of approximately 6-7 nm average diameter assemble to give larger, blackberry-shaped particles with an average diameter of around 35 nm. The Ni NPs were employed as highly efficient catalysts for the selective hydrogenation of C=C double bonds in the aqueous phase under mild reaction conditions (40-90°C at 1.0- 3.0 MPa), and the Ni0 nanocatalysts in the aqueous phase are stable enough to be reused at least seven times without significant loss of catalytic activity during subsequent reuse cycles. 2010 Wiley-VCH Verlag GmbH Co. KGaA, Weinheim.
- Hu, Yu,Yu, Yinyin,Hou, Zhenshan,Yang, Hanming,Feng, Bo,Li, Huan,Qiao, Yunxiang,Wang, Xiangrui,Hua, Li,Pan, Zhenyan,Zhao, Xiuge
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experimental part
p. 1178 - 1184
(2011/07/07)
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- Supramolecular catalyst for aldehyde hydrogenation and tandem hydroformylation-hydrogenation
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The chemoselective reduction of aldehydes and the tandem hydroformylation-hydrogenation of terminal alkenes are possible with a supramolecular catalyst that operates by a novel mechanism involving substrate activation by hydrogen bonding and subsequent metalligand bifunctional hydrogenation (see scheme).
- Diab, Lisa,Smejkal, Tomas,Geier, Jens,Breit, Bernhard
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supporting information; experimental part
p. 8022 - 8026
(2010/02/28)
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- Room-temperature Ru(II)-catalyzed transfer hydrogenation of ketones and aldehydes in air
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Transfer hydrogenation (TH) of ketones and aldehydes was efficiently carried out in 2-propanol at room temperature by means of a ruthenium(II) complex catalyst bearing a 2-(benzoimidazol-2-yl)-6-(pyrazol-1-yl)pyridine ligand. TH of the ketone substrates proceeded in air, reaching final TOFs of up to 59,400 h-1, and the reduction of aldehydes proceeded under a nitrogen atmosphere to achieve final TOFs of up to 5940 h-1.
- Zhao, Miao,Yu, Zhengkun,Yan, Shenggang,Li, Yang
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scheme or table
p. 4624 - 4628
(2009/10/26)
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