- Selective pyrolysis of bifunctional compounds: gas-phase elimination of carbonate-ester functionalities
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Compounds containing both carbonate and ester functionalities were synthesized and then subjected to online-GC gas-phase pyrolysis. The carbonate groups were cleaved selectively in all elimination reactions. The end products of the reaction were found to be affected by the nature of the substrate. The presence of hydrogen and carbonyl substituents on the carbon β to the carbonate group resulted in further product decomposition through a concerted six-membered transition state. Results from flash vacuum pyrolysis (FVP) and analysis of the GC data indicate that the cleavage of the carbonate group is fast, and that the slower secondary decomposition reactions are independent of the presence of the carbonate group. Spectroscopic analyses of the products are reported.
- Al-Azemi, Talal F.,Dib, Hicham H.,Al-Awadi, Nouria A.,El-Dusouqui, Osman M.E.
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- Highly selective transfer hydrogenation of α,β-unsaturated carbonyl compounds using Cu-based nanocatalysts
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Simultaneous dehydrogenation of cyclohexanol to cyclohexanone and hydrogenation of α,β-unsaturated carbonyl compounds to corresponding α,β-unsaturated alcohols was carried out in a single pot reaction without addition of any external hydrogen donor. Cu nanoclusters supported on nanocrystalline MgO were found to be the active catalyst for the chemoselective transfer hydrogenation of unsaturated carbonyl compounds to produce the corresponding alcohols with very high yields. Transfer hydrogenation of cyclohexanol and cinnamaldehyde produced cyclohexanone and cinnamyl alcohol with 100% selectivity. This Cu/MgO catalyst can be easily recovered and recycled up to more than five times without any significant loss of activity, which confirmed the true heterogeneous nature of this catalyst. Several α,β-unsaturated compounds were also tested for this reaction and it was found that for all the cases the yield is >95%. The ease of handling without requiring high pressure H2 or a hazardous hydrogen source makes this transfer hydrogenation more practical and useful.
- Siddqui, Nazia,Sarkar, Bipul,Pendem, Chandrashekar,Khatun, Rubina,Sivakumar Konthala,Sasaki, Takehiko,Bordoloi, Ankur,Bal, Rajaram
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- IR study of alkene allylic activation on magnesium ferrite and alumina catalysts
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The interaction of propene and butenes with oxydehydrogenation catalyst, MgFe2O4, and with an isomerization catalyst, γ-Al2O3, have been studied by FTIR spectroscopy.Allyloxy species (prop-2-en-1-oxides from propene and but-3-en-2-oxide from but-1-ene) were observed over MgFe2O4, while allyl species (prop-2-en-1-yl from propene, but-3-en-2-yl from but-1-ene and 2-methylprop-2-en-1-yl from isobutene), thought to be ?-bonded to Al3+ ions, were observed over γ-Al2O3.It is proposed that on all cases the allylic C-H bond is heterolytically broken at cation-anion couples (Mn+O2-) to give rise to anionic allyls.However, when the cation is reducible, as on the Fe3+ centers of magnesium ferrite, the allyl anion is further rapidly oxidized to allyloxy species that, at high temperature, can act as cationic allyls which interact weakly with oxide anions.From propene, the cationic allyls can act as symmetric species, as is expected for acrolein synthesis.
- Busca, Guido,Finocchio, Elisabetta,Lorenzelli, Vincenzo,Trombetta, Marcella,Rossini, Stefano A.
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- The remarkable promotion of in situ formed Pt-cobalt oxide interfacial sites on the carbonyl reduction to allylic alcohols
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Pt catalysts attract increasing attention for selectively hydrogenating α,β-unsaturated aldehydes to produce allylic alcohols, thanks to their relatively satisfactory selectivity towards the reduction of C[dbnd]O bond over C[dbnd]C bond. Here, new carbon supported cobalt oxide-decorated platinum nanocatalysts for highly selective hydrogenation of cinnamaldehyde were fabricated via a facile composite precursor route. As-fabricated cobalt oxide-decorated Pt catalyst at a Co/Pt atomic ratio of 0.6 was found to exhibit an exceptional catalytic performance with an extremely high 99% yield of cinnamyl alcohol under mild reaction conditions (2 MPa H2 and 80 °C). In contrast to that of the undecorated Pt one, the intrinsic activity of the cobalt oxide-decorated Pt-based one, i.e. the turnover frequency for cinnamaldehyde conversion (4.19 s?1), was significantly increased by 9.5 times. The present catalyst system presents a particularly dramatic enhancement in catalytic performance, in comparison with other Pt-based hydrogenation catalysts previously reported. Such exceptional catalytic efficiency was probably corelated with unique geometric and electronic modifications of Pt particles by CoOx species, thereby giving rise to both the increased exposed active metal surface and the favorable electron-rich state of Pt0 species. Correspondingly, the rate of cinnamaldehyde conversion could be improved and the adsorption of the carbonyl group could be strengthened. This synergy between CoOx species and Pt sites is accounted for the observed superiority of CoOx-decorated Pt catalyst to Co-free Pt one in selective hydrogenation of carbonyl compounds.
- Li, Chenyue,Ke, Changxuan,Han, Ruirui,Fan, Guoli,Yang, Lan,Li, Feng
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- DEPLACEMENTS HOMOLYTIQUES INTRAMOLECULAIRES III-DECOMPOSITION DU PEROXYDE D'ALLYLE ET DE t-BUTYLE DANS LES ETHERS ET LES CYCLANES: EPOXY-2,3 PROPANATION DE CES SOLVANTS
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Product analysis of the thermolysis of allyl t-butyl peroxide in cyclohexane and tetrahydrofuran shows that an important induced decomposition of the peroxide occurs by the addition of radicals derived from the solvent, to the peroxide double bond, followed by an intramolecular homolytic displacement of the t-butoxyl group.Such a reaction is a 2,3-epoxypropanation of the solvent in which the initiator is decomposed.The reaction is shown to be general, by using other ethers and cycloalkanes as solvents.
- Maillard, B.,Montaudon, E.,Rakotomanana, F.,Bourgeois, M. J.
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- EFFECT OF THE STRUCTURE OF SUBSTITUTED PROPARGYL AND ALLYL ALCOHOLS ON THE RATE OF THEIR LIQUID PHASE HYDROGENATION ON A Pd-Ru ALLOY MEMBRANE CATALYST
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The rates of hydrogenation of substituted propargyl and allyl alcohols in the liquid phase on a Pd-Ru alloy membrane catalyst are described by a two-parameter Taft equation which takes into account the inductive and steric effects of the substituents.The values of the parameters at 363 K with H2 at atmospheric pressure are: ρ* = -0.20, δ = 0.10 and ρ+ = -1.1, δ = 1.3 respectively.
- Karavanov, A. N.,Gryaznov, V. M.
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- Co-metathesis of ethylene and olefinic compounds in ionic liquids
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Tungsten(VI) chloride dissolved in the ionic liquids is capable of catalyzing metathesis of 4-octene and co-metathesis of 4-penten-1-ol with ethylene; the latter reaction is preceded by double bond shift in the starting alkenol.
- Greish, Alexander A.,Kustov, Leonid M.,Vasnev, Alexander V.
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- The decomposition of aliphatic N-nitro amines in aqueous sulfuric acid. Bisulfate as a nucleophile
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In aqueous sulfuric acid, aliphatic N-nitro amines decompose to N2O and alcohols. An excess acidity analysis of the observed rate constants for the reaction shows that free carbocations are not formed. The reaction is an acid-catalyzed SN2 displacement from the protonated aci-nitro tautomer, the nucleophile being a water molecule at acidities below 82-85% H2SO4, and a bisulfate ion at higher acidities. Bisulfate is the poorer nucleophile by a factor of about 1000. Twelve compounds were studied, of which results obtained for nine at several different temperatures enabled calculation of activation parameters for both nucleophiles. The reaction appears to be mainly enthalpy controlled. The intercept standard-state rate constants are well correlated by the σ* values for the alkyl groups; the slopes are negative, with a more negative value for the slower bisulfate reaction. Interestingly the m?m* slopes also correlate with σ*, although the scatter is bad.
- Cox, Robin A.
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- Selective hydrogenation of the C=O bond in acrolein through the architecture of bimetallic surface structures
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In the current study we have performed experimental studies and density functional theory (DFT) modeling to investigate the selective hydrogenation of the C=O bond in acrolein on two bimetallic surface structures, the subsurface Pt-Ni-Pt(111) and surface Ni-Pt-Pt(111). We have observed for the first time the production of the desirable unsaturated alcohol (2-propenol) on Pt-Ni-Pt(111) under ultra-high vacuum conditions. Furthermore, our DFT modeling revealed a general trend in the binding energy and bonding configuration of acrolein with the surface d-band center of Pt-Ni-Pt(111), Ni-Pt-Pt(111), and Pt(111), suggesting the possibility of using the value of the surface d-band center as a parameter to predict other bimetallic surfaces for the selective hydrogenation of acrolein.
- Murillo, Luis E.,Goda, Amit M.,Chen, Jingguang G.
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- Synthesis of allyl alcohol as a method to valorise glycerol from the biodiesel production
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Reaction of triglycerides with trimethyl orthoformate in presence of camphorsulfonic acid (CSA) gave the fatty acid methyl esters (FAMEs, 4) in good yield. However, under these conditions, the protected glycerol could not be obtained. Formation of orthoesters 9 was possible in a separate reaction using very weak acidic conditions, namely catalytic amounts of pyridinium para-toluenesulfonate (PPTS). Subjecting the orthoesters 9 to thermolysis at 270 °C gave allyl alcohol (11) with good efficiency.
- Wormann, Michael,Maier, Martin E.
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- Kinetics and mechanism of diallyl sulfoxide pyrolysis; A combined theoretical and experimental study in the gas phase
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A combined experimental and computational study was carried out on the gas phase pyrolysis reaction of diallylsulfoxide. Allyl alcohol and thioacrolein were detected as the major products during a unimolecular reaction. Experimental kinetic studies were carried out via a static system under the pressure of 21-55 torr and temperature of 435.2-475.1 K. Based on the experiments, the reaction is homogeneous and proceeds through a zwitterionic intermediate. Computational studies at the DFT (B3LYP) and QCISD(T) levels with 6-311++G(d,p) basis set indicated a two-step concerted pathway as the possible route. Comparison between the experimental and theoretical activation parameters for the most probable path confirmed a good agreement.
- Izadyar,Gholami
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- Investigation of reaction routes for direct conversion of glycerol over zirconia-iron oxide catalyst
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Conversion of glycerol to useful chemicals was examined using a zirconia-iron oxide catalyst. An aqueous glycerol solution was used as feedstock, and the catalytic reaction was carried out in a fixed-bed flow reactor at 623 K under atmospheric pressure. Useful chemicals, for example propylene, allyl alcohol, carboxylic acids, and ketones, were obtained from the aqueous glycerol solution. The reaction was found to involve a series of consecutive reactions, with allyl alcohol and carboxylic acids as reaction intermediates which were converted to propylene and ketones, respectively. Moreover, the catalyst had high and stable activity in the reaction of a 50 wt% glycerol solution.
- Yoshikawa, Takuya,Tago, Teruoki,Nakamura, Ayaka,Konaka, Aya,Mukaida, Mitsushi,Masuda, Takao
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- The influence of SiO2 doping on the Ni/ZrO2 supported catalyst for hydrogen production through the glycerol steam reforming reaction
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The glycerol steam reforming (GSR) reaction for H2 production was studied comparing the performance of Ni supported on ZrO2 and SiO2-ZrO2 catalysts. The surface and bulk properties were determined by ICP, BET, XRD, TPD, TPR, TPO, XPS, SEM and STEM-HAADF. It was suggested that the addition of SiO2 stabilizes the ZrO2 monoclinic structure, restricts the sintering of nickel particles and strengthens the interaction between Ni2+ species and support. It also removes the weak acidic sites and increases the amount of the strong acidic sites, whereas it decreases the amount of the basic sites. Furthermore, it influences the gaseous products’ distribution by increasing H2 yield and not favouring the transformation of CO2 in CO. Thus, a high H2/CO ratio can be achieved accompanying by negligible value for CO/CO2. From the liquid products quantitative analysis, it was suggested that acetone and acetaldehyde were the main products for the Ni/Zr catalyst, for 750 °C, whereas for the Ni/SiZr catalyst allyl alcohol was the only liquid product for the same temperature. It was also concluded that the Ni/SiZr sample seems to be more resistant to deactivation however, for both catalysts a substantial amount of carbon exists on the catalytic surface in the shape of carbon nanotubes and amorphous carbon.
- Charisiou,Papageridis,Siakavelas,Sebastian,Hinder,Baker,Polychronopoulou,Goula
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- Boron-modified chlorine-free K+-FeOx/SBA-15 as highly effective catalyst for propylene epoxidation by nitrous oxide
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Modification of chlorine-free alkali metal ion (K+, Rb +, or Cs+)-containing FeOx/SBA-15 catalysts with boron enhanced their catalytic performances in propylene epoxidation by nitrous oxide. A B-K+-FeOx/SBA-15 catalyst (K/Fe = 2.5, B/Fe = 0.5) showed the best propylene oxide (PO) formation activity, providing PO selectivities of 79 and 55% at propylene conversions of 4.8 and 13% at 350 and 400 °C, respectively. Copyright
- Yang, Sufen,Zhang, Qinghong,Wang, Ye
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- Trend in the C=C and C=O bond hydrogenation of acrolein on Pt-M (M = Ni, Co, Cu) bimetallic surfaces
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Acrolein, the smallest α,β-unsaturated aldehyde, is used as a probe molecule to study the effect on the hydrogenation activity toward the C=C and C=O bonds due to the presence of a 3d transition metal either on the surface or in the subsurface region of a Pt(1 1 1) substrate. Temperature programmed desorption (TPD), high-resolution electron energy loss spectroscopy (HREELS), and density functional theory (DFT) modeling are used to help explain the trend in the overall hydrogenation activity and selectivity toward the corresponding unsaturated alcohol (2-propenol) on the 3d/Pt(1 1 1) bimetallic surfaces. The hydrogenation activity on the subsurface Pt-3d-Pt(1 1 1) structures displays the following trend: Pt- Ni-Pt(1 1 1) > Pt-Co-Pt(1 1 1) > Pt-Cu-Pt(1 1 1) based on the TPD yields. The absolute yield toward 2- propenol is also the highest on Pt-Ni-Pt(1 1 1), which is further enhanced by the presence of preadsorbed hydrogen. In contrast, the selective hydrogenation does not occur on the surface monolayer 3d-Pt(1 1 1) structures. The TPD results are consistent with HREELS measurements of different vibrational features after the adsorption and reaction of acrolein on the subsurface Pt-3d-Pt(1 1 1) and surface 3d-Pt(1 1 1) structures. In addition, DFT calculations suggest that the different hydrogenation activities between the subsurface and surface structures appear to be related to the differences in the binding energy of acrolein on the corresponding bimetallic surfaces.
- Murillo, Luis E.,Menning, Carl A.,Chen, Jingguang G.
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- SELECTIVE CATALYTIC HYDROGENATION OF PROPARGYL ALCOHOL WITH HETEROPOLY ACID-MODIFIED PALLADIUM
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The Keggin type heteropoly acid was readily reduced with hydrogen in the aqueous phase at 30 deg C in the presence of Pd(II) or metallic Pd, taking up 1 to 11 molecules of hydrogen per Keggin unit.The palladium catalyst prepared by the H2-reduction of an aqueous solution containing Pd(II) and heteropoly acid was very effective for the aqueous-phase selective semihydrogenation of propargyl alcohol.
- Izumi, Yusuke,Tanaka, Yoshiyuki,Urabe, Kazuo
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- HETEROGENEOUS ASYMMETRIC RING-OPENING REACTIONS OF PROCHIRAL EPOXIDES INCLUDED AS GUEST MOLECULES IN TRI-o-THYMOTIDE CLATHRATES.
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Enantiomorphous tri-o-thymotide clathrates of prochiral oxiranes were submitted to the action of gaseous hydrogen halides.Ring-opening reactions ensued that differ from those reported in homogeneous phase, showing a considerable modification of the chemical reactivity of the external reagent in the host lattice.Chirality transfer from the host receptors to the guest products was also observed, but with a poor efficiency.
- Gerdil, Raymond,Barchietto, Giacomo
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- A study on the cataluminescence of propylene oxide on FeNi layered double hydroxides/graphene oxide
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In this work, FeNi layered double hydroxides/graphene oxide (FeNi LDH/GO) was prepared, which exhibits excellent selective cataluminescent performance towards propylene oxide. The selectivity and sensitivity of the cataluminescence (CTL) reaction were investigated in detail. Moreover, the catalytic reaction mechanism, including the intermediate products and the conversion of reactants to products, was discussed based on both the experimental and computational results. Furthermore, the proposed FeNi LDH/GO based CTL sensor was successfully applied for the determination of propylene oxide residue in fumigated raisins, which indicates extensive application potential for rapid food safety evaluation.
- Li, Ming,Hu, Yufei,Li, Gongke
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- ReOx/TiO2: A Recyclable Solid Catalyst for Deoxydehydration
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Deoxydehydration (DODH) enables the transformation of two adjacent hydroxyl functions into a C-C double bond: e.g., facilitating synthesis of 1,3,5-hexatriene from sorbitol. Here we report the first stable heterogeneous catalyst for DODH based on ReOx supported on TiO2. ReOx/TiO2 exhibits not only catalytic activity and selectivity comparable to those of previously described molecular rhenium catalysts but also excellent stability without deactivation over at least six consecutive runs. X-ray absorption spectroscopy (XAFS) measurements indicate a mixture of Re(VII), Re(IV), and Re(0) species at a ratio of 0.47:0.27:0.25, remaining comparatively stable during catalysis.
- Sandbrink, Lennart,Klindtworth, Elisabeth,Islam, Husn-Ubayda,Beale, Andrew M.,Palkovits, Regina
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- ANOMALOUS SOLVOLYSIS OF A POLYENOL ETHER OF GLYCEROL
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Fecapentaene-12 1 displays an unexpected reactivity when treated with hydrochloric acid in aqueous solvents.Instead of forming the unsubstituted aldehyde 2,4,6,8-dodecatetraenal 2, a completely different pathway is observed, resulting in the exclusive formation of 10-methoxy-2,4,6,8-dodecatetraenal 3a (methanol/water) or 10-hydroxy-2,4,6,8-dodecatetraenal 3b (tetrahydrofuran/water).
- Vertegaal, L. B. J.,Steeg, M. Van Der,Gen, A. Van Der
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- Supported gold nanoparticles from quantum dot to mesoscopic size scale: Effect of electronic and structural properties on catalytic hydrogenation of conjugated functional groups
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Titania- and zirconia-supported gold particles of 1-5 nm size, prepared by various routes of synthesis, were employed in the partial hydrogenation of acrolein. In-depth characterization of their structural and electronic properties by electron microscopy, electron paramagnetic resonance, and optical absorption spectroscopy aimed at disclosing the nature of the active sites controlling the hydrogenation of C=O vs C=C bonds. The structural characteristics of the catalysts, as mean particle size, size distribution, and dispersion, distinctly depend on the synthesis applied and the oxide support used whereby the highest gold dispersion (D(Au) = 0.78, Au/TiO2) results from a modified sol-gel technique. For extremely small gold particles on titania and zirconia (1.1 and 1.4 nm mean size), conduction electron spin resonance of the metal and paramagnetic F-centers (trapped electrons in oxygen vacancies) of the support were observed. Besides the influence of the surface geometry on the adsorption mode of the α,β-unsaturated aldehyde, the marked structure sensitivity of the catalytic properties with decreasing particle size is attributed to the electron-donating character of paramagnetic F-centers forming electron-rich gold particles as active sites. The effect of structural and electronic properties due to the quantum size effect of sufficiently small gold particles on the partial hydrogenation is demonstrated.
- Claus,Bruckner,Mohr,Hofmeister
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- A Simple and Efficient Procedure for Rh(I)- and Ir(I)-complex Catalyzed Para-hydrogenation of Alkynes and Alkenes in Aqueous Media Resulting in Strong PHIP Effects
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Catalytic hydrogenations with para-H2 may lead to strong para-hydrogen induced polarization (PHIP) and the hyperpolarized probe molecules may enable the application of the Magnetic Resonance Imaging (MRI) diagnostic modality for metabolism imaging. The use of water as a solvent for para-hydrogenation reactions is very challenging due to the fast exchange between the catalytically active metal hydrides and the water protons and also because of the low hydrogen solubility in water. Here we report that several water-soluble Rh(I)- and Ir(I)-complexes with N-heterocyclic carbene (NHC) and/or tertiary phosphine ligands efficiently catalyze the synthesis of hyperpolarized compounds by para-hydrogenation in aqueous media.
- Papp, Gábor,Horváth, Henrietta,Joó, Ferenc
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- Three Consecutive Allylic Sigmatropic Rearrangements of 1,8-Bis(allylthio)naphthalene Monooxides via Transannular Interaction
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Oxidation of 1,8-bis(allylthio)naphthalene with m-chloroperbenzoic acid (mCPBA) gave the monooxide which undergoes three consecutive sigmatropic rearrangements to afford 2-allylnaphtho-1,2-dithiole; the mechanism has been studied using deuterium tracer experiments.
- Furukawa, Naomichi,Shima, Hidetaka,Kimura, Takeshi
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- One-step synthesis of ethanol from glycerol in a gas phase packed bed reactor over hierarchical alkali-treated zeolite catalyst materials
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The gas-phase conversion of glycerol into ethanol in a "green" one-step synthesis over a cesium metal-promoted zeolite catalyst has been reported for the first time. To our knowledge, the CsZSM-5 based catalyst presented in this work showed one of the best yields of ethanol in the gas-phase glycerol conversion. The catalyst sample's structure, texture, and acid-base properties were characterized using numerous materials characterization techniques. The catalytic evaluation was carried out in a packed-bed continuous flow reactor. The highest ethanol yield achieved was 99.6 mol% over a 20 wt% CsZSM-5 catalyst with SiO2/Al2O3 = 1500, 10 wt% glycerol feed concentration, 350 °C reaction temperature, and GHSVtotal = 625 h-1. It was demonstrated that the best catalytic performance was related to the ample amount of surface basic sites, synergistic interaction between Cs species and the HZSM-5 zeolite and to its smaller crystallite size obtained from XRD analysis. The achieved results exhibit great potential of utilizing the alkali-treated CsZSM-5 catalyst for the gas-phase conversion of glycerol into bio-based ethanol. The possible reaction route from glycerol to renewable ethanol was proposed based on direct glycerol conversion to ethanol via the thermal monodehydration, radical fragmentation, methylation and transfer hydrogenation reactions. Finally, for the first time, methanol was directly converted into ethanol in the gas-phase continuous flow packed-bed reactor over a 20 wt% CsZSM-5 catalyst.
- Kostyniuk, Andrii,Bajec, David,Likozar, Bla?
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- Direct Synthesis of Propene Oxide by using an EuCl3 Catalytic System at Room Temperature
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Epoxidation of propene to propene oxide with O2 is catalysed by an EuCl3-Zn-MeCO2H catalytic system at 30 deg C (TON of 12.1 in 1 h).
- Yamanaka, Ichiro,Nakagaki, Katsumi,Otsuka, Kiyoshi
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- The radiosynthesis of no-carrier added [1-11C]allyl alcohol evidence for the formation of a new reducing species: Lithium aluminium hydride - vinylmagnesium bromide
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Lithium aluminium hydride in the presence of vinylmagnesium bromide (1:1 molar ratio) affords a potent reagent for the reduction of acrylic acid to allyl alcohol (ratio of allyl alcohol to 1-propanol: 3:2). This reducing mixture has allowed the preparation of no-carrier added [1-11C]allyl alcohol with a 25% yield (decay corrected at the end of radionuclide production overall synthesis time including GC: 40 min in a one step procedure from [11C]carbon dioxide (C-11:t 1/2 : 20.4 min). [1-11C]1-propanol was obtained in parallel with a 6.5% yield.
- Lasne,Moreau,Cairon,Barre
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- Spectators Control Selectivity in Surface Chemistry: Acrolein Partial Hydrogenation over Pd
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We present a mechanistic study on selective hydrogenation of acrolein over model Pd surfaces-both single crystal Pd(111) and Pd nanoparticles supported on a model oxide support. We show for the first time that selective hydrogenation of the C=O bond in acrolein to form an unsaturated alcohol is possible over Pd(111) with nearly 100% selectivity. However, this process requires a very distinct modification of the Pd(111) surface with an overlayer of oxopropyl spectator species that are formed from acrolein during the initial stages of reaction and turn the metal surface selective toward propenol formation. By applying pulsed multimolecular beam experiments and in situ infrared reflection-absorption spectroscopy, we identified the chemical nature of the spectator and the reactive surface intermediate (propenoxy species) and experimentally followed the simultaneous evolution of the reactive intermediate on the surface and formation of the product in the gas phase.
- Dostert, Karl-Heinz,OBrien, Casey P.,Ivars-Barceló, Francisco,Schauermann, Swetlana,Freund, Hans-Joachim
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- Selective Hydrogenation of Crotonaldehyde to Crotyl Alcohol on Ag-MnO2/Al2O3*5AlPO4 Catalysts
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The activity and selectivity of Ag-MnO2/Al2O3*5AlPO4 catalysts for the hydrogenation of crotonaldehyde to crotyl alcohol have been investigated in liquid phase.When MnO2 was added to the catalyst, the activity and selectivity for the reaction were remarkably improved to give the conversion of 100 molpercent and the selectivity of 69.5percent.
- Nagase, Yoshinori,Muramatu, Hideaki,Sato, Takuzi
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- Identification of active sites in gold-catalyzed hydrogenation of acrolein
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The active sites of supported gold catalysts, favoring the adsorption of C=O groups of acrolein and subsequent reaction to allyl alcohol, have been identified as edges of gold nanoparticles. After our recent finding that this reaction preferentially occurs on single crystalline particles rather than multiply twinned ones, this paper reports on a new approach to distinguish different features of the gold particle morphology. Elucidation of the active site issue cannot be simply done by varying the size of gold particles, since the effects of faceting and multiply twinned particles may interfere. Therefore, modification of the gold particle surface by indium has been used to vary the active site characteristics of a suitable catalyst, and a selective decoration of gold particle faces has been observed, leaving edges free. This is in contradiction to theoretical predictions, suggesting a preferred occupation of the low-coordinated edges of the gold particles. On the bimetallic catalyst, the desired allyl alcohol is the main product (selectivity 63%; temperature 593 K, total pressure ptotal = 2 MPa). From the experimentally proven correlation between surface structure and catalytic behavior, the edges of single crystalline gold particles have been identified as active sites for the preferred C=O hydrogenation.
- Mohr, Christian,Hofmeister, Herbert,Radnik, Joerg,Claus, Peter
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- Structural properties of Ag/TiO2 catalysts for acrolein hydrogenation
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We have successfully employed Ag/TiO2 catalysts (metal loading, 7 wt %) in the gas-phase hydrogenation of acrolein, the α,β- unsaturated aldehyde which is the most difficult to hydrogenate at the carbonyl group. The relations of the structural characteristics and surface state of these catalysts with respect to their activity and selectivity have been studied by surface analytical techniques (XPS, UPS, ISS) and magnetic resonance (ESR). The catalysts, consisting of titania-supported silver nanoparticles of less than 3 nm mean size, have been formed by various pretreatment procedures including low-temperature reduction at 473 K (LTR) and high-temperature reduction at 700 or 773 K (HTR). The unexpected finding of smaller silver nanoparticles of ≈1.5 nm mean diameter upon high-temperature reduction as compared to ≈3 nm mean diameter upon low-temperature reduction points to growth inhibition by Ti suboxide overlayers (several atomic layers thick) due to strong metal-support interaction, being the more pronounced the higher the reduction temperature applied. This interaction also leads to a truncated particle morphology deviating from spherical shape. The effect of both increasing particle coverage by TiOx and decreasing particle size, as obtained by high-temperature reduction, results in a decrease of the catalyst activity and selectivity to allyl alcohol. This behavior and the absence of Ti3+ at the very catalyst surface point to the fact that, different from the case of catalysts such as Pt/TiO2, TiOx/Ti3+ species do not act as special sites for carbonyl group activation with our Ag/TiO2 catalysts. With the LTR catalyst, the specific activity was 1 order of magnitude higher, compared to the HTR catalyst, and was accompanied by the formation of allyl alcohol with a much larger selectivity (LTR, 42%; HTR, 27%).
- Grünert, Wolfgang,Brückner, Angelika,Hofmeister, Herbert,Claus, Peter
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- Operando Investigation of Ag-Decorated Cu2O Nanocube Catalysts with Enhanced CO2 Electroreduction toward Liquid Products
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Direct conversion of carbon dioxide into multicarbon liquid fuels by the CO2 electrochemical reduction reaction (CO2RR) can contribute to the decarbonization of the global economy. Here, well-defined Cu2O nanocubes (NCs, 35 nm) uniformly covered with Ag nanoparticles (5 nm) were synthesized. When compared to bare Cu2O NCs, the catalyst with 5 at % Ag on Cu2O NCs displayed a two-fold increase in the Faradaic efficiency for C2+ liquid products (30 % at ?1.0 VRHE), including ethanol, 1-propanol, and acetaldehyde, while formate and hydrogen were suppressed. Operando X-ray absorption spectroscopy revealed the partial reduction of Cu2O during CO2RR, accompanied by a reaction-driven redispersion of Ag on the CuOx NCs. Data from operando surface-enhanced Raman spectroscopy further uncovered significant variations in the CO binding to Cu, which were assigned to Ag?Cu sites formed during CO2RR that appear crucial for the C?C coupling and the enhanced yield of liquid products.
- Herzog, Antonia,Bergmann, Arno,Jeon, Hyo Sang,Timoshenko, Janis,Kühl, Stefanie,Rettenmaier, Clara,Lopez Luna, Mauricio,Haase, Felix T.,Roldan Cuenya, Beatriz
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- Composition of tungsten oxide bronzes active for hydrodeoxygenation
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We explore the composition of reduced tungsten oxide bronze materials as a new class of heterogeneous catalysts for hydrodeoxygenation of bio-fuels. We demonstrate a method using thermogravimetric analysis (TGA) and mass spectrometry to determine both the oxygen substoichiometry and hydrogen content of the HyWO3-z catalytic phase that is formed during hydrogen pretreatment at temperatures from 200 to 500 °C. Results for three WO3 materials show that the composition depends on crystallinity and surface area, as well as pretreatment temperature and time. The optimal pretreatment conditions for hydrogenation of acrolein to allyl alcohol at 50 °C occur over a narrow temperature range around 350 °C. We report for the first time that at higher reaction temperatures the catalysts are active for hydrodeoxygenation of allyl alcohol to propene and 1,5-hexadiene. We have proposed a mechanism similar to the Mars-van Krevelen cycle in which an alcohol adsorbs on an oxygen vacancy, forming a tungsten-oxygen bond and breaking the carbon-oxygen bond. Our TGA and reaction kinetics data indicate that the composition of the active catalyst is between H0.9WO2.9 and H1.3WO2.7 and that the rate of hydrodeoxygenation is comparable to the oxygen vacancy creation rate.
- Thibodeau, Timothy J.,Canney, Alexander S.,Desisto, William J.,Wheeler, M. Clayton,Amar, Franois G.,Frederick, Brian G.
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- Vapour phase transfer hydrogenation of α,β-unsaturated carbonyl compounds. Thermodynamic and experimental studies
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This paper presents the first systematic thermodynamic study of the vapour phase transfer hydrogenation of α,β-unsaturated carbonyl compounds at temperatures: 423.15-723.15 K. Calculations were made for four compounds, namely: acrolein, α-methylacrolein, β-methylacrolein and methyl vinyl ketone. The Gibbs free energies and equilibrium mole fractions (EMFs) were calculated for transfer hydrogenation with ethanol and 2-propanol as hydrogen donors. It was noted that for transfer hydrogenation and hydrogenation with hydrogen the formation of the unsaturated alcohol (UOL) is the least thermodynamically favoured reaction and that saturated alcohol (SOL) and saturated aldehyde or ketone (SAL or SON) are the main products. A set of eight carbonyl compounds have been transfer hydrogenated with ethanol and 2-propanol in the presence of MgO as the catalyst. The main conclusions are that: (a) the reduction of a carbonyl group into a carbinol group occurs with a very high selectivity, (b) for almost all carbonyl compounds, except acrolein, the reactivity of 2-propanol highly exceeded that shown by ethanol and (c) the high chemoselectivity of transfer hydrogenation of acrolein with alcohols resulted from the kinetic control caused by the presence of magnesium oxide.
- Gliński, Marek,Ulkowska, Urszula
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- Towards the "pressure and materials gap": Hydrogenation of acrolein using silver catalysts
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The hydrogenation of acrolein has been studied over various Ag/SiO2 catalysts in a pressure range from 50 mbar to 20 bar. Increasing partial pressures of acrolein and/or hydrogen lead to increasing selectivities of allyl alcohol. The selectivity towards allyl alcohol also depends on the structural features of the Ag/SiO2 catalyst. Larger particles seem to favour the production of propanal. This observation is discussed in view of the different plane-to-edge-ratio of the different catalysts. The interaction of hydrogen with silver samples has been studied with TAP at very low pressures as well as with calorimetry at ambient pressures. Both methods indicate, that also the hydrogen adsorption is structure-sensitive. No interaction of hydrogen with electrolytic silver or the support material alone was observed. IR spectroscopy has been used to elucidate the interaction of acrolein with Ag/SiO2 catalysts. A strong interaction with the support material was found, hindering the observation of probable silver-acrolein interaction.
- Bron,Kondratenko,Trunschke,Claus
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- Tailoring Interfacial Lewis Acid-Basic Pair on ZnO/4Mg1ZrOx Allows Dehydrogenative α-Methylenation of Alcohols with Methanol to Allylic Alcohols
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Allylic alcohols are the essential building blocks widely used in diverse streams of organic inventions for pharmaceuticals, fragrances, agrochemicals and polymers. Currently, allylic alcohols are industrially produced from petroleum-based feedstocks via atom uneconomic processes. More sustainable synthesis route for allylic alcohols is limited. Herein, a methodology for the direct and highly selective production of allylic alcohols has been accomplished by controlled dehydrogenative α-methylenation of alcohols with methanol. This transformation is enabled by interfacial Lewis acid-basic pair on tailor-made ZnO/4Mg1ZrOx mixed oxide. High selectivity (83～92%) of allylic alcohols is the consequence of alcohols acceptorless dehydrogenation to liberation of H2 and Meerwein-Ponndorf-Verley type hydrogen transfer onto C = O bonds of unsaturated aldehydes. Furthermore, the prepared ZnO/4Mg1ZrOx mixed oxide shows good stability after 200 h time on stream test. These observations could additionally allow us to design multifunctional solid acid-basic catalysts for the transformations of renewable oxygenates into value-added chemicals.
- Fu, Aixiao,Jiang, Shifeng,Liu, Qiang,Liu, Xiaoran,Liu, Xiuyun,Mu, Xindong,Sun, Mengqing,Wang, Xicheng,Xu, Guoqiang,Zhao, Lingling
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- Influence of the support composition on the hydrogenation of acrolein over Ag/SiO2-Al2O3 catalysts
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The gas phase hydrogenation of acrolein over supported silver catalysts has been investigated with a focus on the influence of the support acidity. Acidity has been varied by preparing silver catalysts supported on silica/alumina supports with varying SiO2/Al2O3 ratio. After the catalytic experiments the Ag catalysts exhibit similar particle sizes, as revealed with TEM (transmission electron microscopy). The acidity of the samples was estimated using TPD of adsorbed ammonia which gives the total acidity of the samples, furthermore by IR of adsorbed pyridine to identify the Bronsted and Lewis acidity. No Bronsted acidity was found, and the Lewis acidity showed a clear dependence on the support composition. It is shown that a high total acidity and a high amount of strong Lewis acid sites on the catalysts cause a low conversion of acrolein and low selectivity to allyl alcohol. The interaction of silver with the support or effects of the metal-support perimeter are discussed as possible reasons for this behaviour.
- Volckmar, Claudia E.,Bron, Michael,Bentrup, Ursula,Martin, Andreas,Claus, Peter
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- PHENYLSELENODESILYLATION OF ALLYLSILANES AND REGIOSPECIFIC TRANSFORMATION OF ALLYLSILANES TO ALLYLIC ALCOHOLS VIA ALLYLSELENIDES
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Allylsilanes were converted regiospecifically to allylselenides by reaction with phenylselenenyl chloride and subsequent treatment with anhydrous tin(II)chloride or florisil.Oxidative work-up of these allylselenides gave the corresponding allylic alcohols regiospecifically.
- Nishiyama, Hisao,Itagaki, Kazuyoshi,Sakuta, Koji,Itoh, Kenji
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- Silicon-directed acid ring-opening of allyltrimethylsilane oxide. X-ray structures of 3-triisopropylsilyl-2-(2,4-dinitrobenzoyloxy)-1-propanol and 3-triisopropylsilyl-2-(2,4,6-trinitrobenzoyloxy)-1-propanol
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Allyltrimethylsilane oxide 5 undergoes regiospecific ring-opening with carboxylic acids in chloroform to give the hydroxy esters 6a-e. In polar solvents competing elimination results in the formation of allyl alcohol. Allyltriisopropylsilane oxide 17 undergoes analogous reactions as 5 in chloroform but does not undergo elimination in methanol or acetone. The X-ray structures of 18b and 18c reveal significant lengthening of the C-O (ester) bond (a remarkable 1.502(2) A for 18c), these structural effects are due to strong σC-Si-σ*C-O interactions, particularly for 18c.
- Badali, Fatmir,Issa, William,Pool, Brett,White, Jonathan M.
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- V- or Mo-modified niobium catalysts for glycerin conversion reactions in the presence of H2O2
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In the present work, amorphous niobium oxides with 5% (w/w) vanadium or molybdenum isomorphically substituted into the material structure were synthesized. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The results show that vanadium and molybdenum were incorporated into the niobium oxide structure with concomitant changes in the morphologic and catalytic properties. Catalytic studies on the conversion of residual glycerin generated during biodiesel production in the presence of H2O2 showed enhanced efficiency of ether formation with the vanadium-containing material. The NbV/ethanol/glycerin/250 °C system was found to convert 80% of glycerin. Experiment-planning studies in conjunction with the analysis of the surface response via gas chromatography-mass spectrometry (GC-MS) aided in the determination of the optimal conditions. The catalytic tests monitored by GC-MS showed the formation a mixture of ethers obtained by the condensation of glycerol. Furthermore, it was observed that the modification of the catalyst directs the formation of larger molecules such as ketone mainly in the catalyst containing vanadium.
- Souza, Juber P.,Melo, Thaís,De Oliveira, Marcone A.L.,Paniago, Roberto M.,De Souza, Patterson P.,Oliveira, Luiz C.A.
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- CORRELATION OF THE RATES OF SOLVOLYSIS OF ALLYL AND BENZYL ARENESULPHONATES
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Analysis of the specific rates of solvolysis of allyl arenesulphonates in terms of the extended Grunwald-Winstein equation indicates a marked dependence on both the solvent nucleophilicity (high/value) and the solvent ionizing power (high m value).As the charge delocalization in the leaving group increases, both l and m values fall.For allyl toluene-p-sulphonate solvolysis in 28 solvents at 50.0 deg C, values for l(0.83) and for m (0.63), based on the use of NKL and Y values, are very similar to the equivalent values of 0.90 and 0.67 previously reported for benzyl toluene-p-sulphonate solvolysis.Related extended Grunwald-Winstein analyses are considered and the need for variety in the choice of solvents is emphasized.
- Kevill, Dennis N.,Rissmann, Thomas J.
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- Allylboration of nitrosobenzene
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The allylboration of nitrosobenzene at -70°C resulted in the formation of N- and O-allyl derivatives of N-phenylhydrazine, which were reduced with the second allylborane molecule to N-allylaniline above 100°C.
- Bubnov, Yurii N.,Pershin, Dmitrii G.,Karionova, Anna L.,Gurskii, Mikhail E.
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- pH optimization of nucleophilic reactions in water
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We present a way of prescribing the pH for a reaction so as to obtain either (a) maximum yield in competition with hydrolysis or (b) selective reaction at either of two sites in such nucleophile-electrophile reactions as C-alkylation of acidic ketones and the acylation and sulfonylation of amines. First, we derive the following general equation for pHmax, the pH giving the highest yield of the product (P) of the reaction of a nucleophile (Nu) with a hydrolyzable electrophile (E) in water: pHmax = 1/2[log (kw/kOH) + PKw + pKw] (kw and kOH refer to the water- and hydroxide-promoted hydrolyses of E, Kw is the autoprotolysis constant of water, and Ka is the acid dissociation constant of NuH+, the conjugate acid of Nu). pHmax thus depends on a property of E (namely, kw/kOH) and a property of Nu (the pKa of NuH+), but not on the rate constant for the reaction of E with Nu or the concentration of Nu. We then deduce analogous approximate equations for maximum selectivity for reaction at either of two nucleophilic sites, specifically, equations giving pHxmax and pHymax, the pH values for the maximum yields of the respective products (Px and Py) of the reactions of E with the two nucleophiles. We find that (a) pH-yield profiles calculated from the equations concur with observed yields for reactions under pseudo-first-order conditions and (b) preparative experiments at the estimated pH values give good to excellent yields of clean products and high selectivity in both the C-alkylation and Schotten-Baumann reactions.
- King,Rathore,Lam,Guo,Klassen
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- Deprotection of benzyl and p-methoxybenzyl ethers by chlorosulfonyl isocyanate-sodium hydroxide
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CSI-NaOH procedure provided a new and mild methodology for the deprotection of benzyl and p-methoxybenzyl ethers without affecting the other functional groups under similar reaction conditions.
- Kim, Ji Duck,Han, Gyoonhee,Zee, Ok Pyo,Jung, Young Hoon
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- Revisiting the deoxydehydration of glycerol towards allyl alcohol under continuous-flow conditions
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The deoxydehydration (DODH) of glycerol towards allyl alcohol was revisited under continuous-flow conditions combining a microfluidic reactor setup and a unique reactive dynamic feed solution approach. Short reaction times, high yield and excellent selectivity were achieved at high temperature and moderate pressure in the presence of formic acid, triethyl orthoformate, or a combination of both. Triethyl orthoformate appeared as a superior reagent for the DODH of glycerol, with shorter reaction times, lower reaction temperatures and more robust conditions. In-line IR spectroscopy and computations provided different perspectives on the unique reactivity of glycerol O,O,O-orthoesters.
- Tshibalonza, Nelly Ntumba,Monbaliu, Jean-Christophe M.
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- Selective Hydrogenation of Acrolein Over Pd Model Catalysts: Temperature and Particle-Size Effects
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The selectivity in the hydrogenation of acrolein over Fe3O4-supported Pd nanoparticles has been investigated as a function of nanoparticle size in the 220–270 K temperature range. While Pd(111) shows nearly 100 % selectivity towards the desired hydrogenation of the C=O bond to produce propenol, Pd nanoparticles were found to be much less selective towards this product. In situ detection of surface species by using IR-reflection absorption spectroscopy shows that the selectivity towards propenol critically depends on the formation of an oxopropyl spectator species. While an overlayer of oxopropyl species is effectively formed on Pd(111) turning the surface highly selective for propenol formation, this process is strongly hindered on Pd nanoparticles by acrolein decomposition resulting in CO formation. We show that the extent of acrolein decomposition can be tuned by varying the particle size and the reaction temperature. As a result, significant production of propenol is observed over 12 nm Pd nanoparticles at 250 K, while smaller (4 and 7 nm) nanoparticles did not produce propenol at any of the temperatures investigated. The possible origin of particle-size dependence of propenol formation is discussed. This work demonstrates that the selectivity in the hydrogenation of acrolein is controlled by the relative rates of acrolein partial hydrogenation to oxopropyl surface species and of acrolein decomposition, which has significant implications for rational catalyst design.
- O'Brien, Casey P.,Dostert, Karl-Heinz,Schauermann, Swetlana,Freund, Hans-Joachim
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- Effect of MgCl2 in vapor-phase hydrogen transfer reaction between acrolein and 2-propanol over MgO catalyst systems
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Vapor-phase hydrogen transfer reaction between acrolein and 2-propanol over MgO catalyst systems has investigated. We found that, particularly at early reaction time, both the high activity and remarkable increase of allyl alcohol selectivity were achieved by the addition of a small amount of MgCl2 on MgO catalyst.
- Nagase, Yoshinori,Katou, Tokumitsu
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- Catalytic deoxydehydration of glycols with alcohol reductants
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Top shelf dehydration: Ammonium perrhenate catalysts combined with benzylic alcohol reductants are used for the efficient deoxydehydration of glycols to olefins. The olefin and aldehyde products can be easily separated and isolated. It is also demonstrated that the catalyst can be recovered and reused because of its low solubility in aromatic solvents.
- Boucher-Jacobs, Camille,Nicholas, Kenneth M.
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- Cationic Ru complexes anchored on POM via non-covalent interaction towards efficient transfer hydrogenation catalysis
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The ionic materials consisting of cationic Ru complexes and Wells-Dawson polyoxometalate anion (POM, K6P2W18O62) have been constructed via a non-covalent interaction. The as-synthesized catalysts have been characterized thoroughly by NMR, XRD, FESEM, and FT-IR, etc. The characterization suggested that a hydrogen bond interaction occurred between the proton of the amine ligand in the cationic Ru complexes and the oxygen atom of the POM anion. The hydrogen bond played an important role in enhancing catalytic activity for the transfer hydrogenation of methyl levulinate (ML) to γ-valerolactone (GVL) under very mild conditions. Especially, the transfer hydrogenation reaction proceeded via a heterogeneous catalysis approach and the heterogenized catalysts even afforded much better catalytic performance than homogeneous analogs. Notably, the catalysts can be recycled without an obvious loss of activity, and further extended to highly selective transfer hydrogenation of α,β-unsaturated ketones and aldehydes, etc. into the corresponding α,β-unsaturated alcohols without any base external additives. The high catalytic performance of these anchored catalysts was highly related to the hydrogen bond interaction and the basicity of the polyanion. The obtained knowledge from this work could lead us to a new catalysis concept of tethering active homogeneous complexes for constructing highly active anchored Ru complex catalysts for hydrogenation reaction.
- Chen, Manyu,Cui, Kai,Hou, Zhenshan,Peng, Qingpo,Wang, Jiajia,Wei, Xinjia,Zhao, Xiuge
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- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- Parahydrogen-Induced Polarization Relayed via Proton Exchange
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The hyperpolarization of nuclear spins is a game-changing technology that enables hitherto inaccessible applications for magnetic resonance in chemistry and biomedicine. Despite significant advances and discoveries in the past, however, the quest to establish efficient and effective hyperpolarization methods continues. Here, we describe a new method that combines the advantages of direct parahydrogenation, high polarization (P), fast reaction, and low cost with the broad applicability of polarization transfer via proton exchange. We identified the system propargyl alcohol + pH2 → allyl alcohol to yield 1H polarization in excess of P ≈ 13% by using only 50% enriched pH2 at a pressure of ≈1 bar. The polarization was then successfully relayed via proton exchange from allyl alcohol to various target molecules. The polarizations of water and alcohols (as target molecules) approached P ≈ 1% even at high molar concentrations of 100 mM. Lactate, glucose, and pyruvic acid were also polarized, but to a lesser extent. Several potential improvements of the methodology are discussed. Thus, the parahydrogen-induced hyperpolarization relayed via proton exchange (PHIP-X) is a promising approach to polarize numerous molecules which participate in proton exchange and support new applications for magnetic resonance.
- Them, Kolja,Ellermann, Frowin,Pravdivtsev, Andrey N.,Salnikov, Oleg G.,Skovpin, Ivan V.,Koptyug, Igor V.,Herges, Rainer,H?vener, Jan-Bernd
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supporting information
p. 13694 - 13700
(2021/09/07)
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- Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
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The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
- Fiorio, Jhonatan L.,Rossi, Liane M.
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p. 312 - 318
(2021/01/29)
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- Dehydrogenative alcohol coupling and one-pot cross metathesis/dehydrogenative coupling reactions of alcohols using Hoveyda-Grubbs catalysts
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In this study,in situformed ruthenium hydride species that were generated from Grubbs type catalysts are used as efficient catalysts for dehydrogenative alcohol coupling and sequential cross-metathesis/dehydrogenative coupling reactions. The selectivity of Grubbs first generation catalysts (G1) in dehydrogenative alcohol coupling reactions can be tuned for the ester formation in the presence of weak bases, while the selectivity can be switched to the β-alkylated alcohol formation using strong bases. The performance of Hoveyda-Grubbs 2nd generation catalyst (HG2) was improved in the presence of tricyclohexylphosphine for the selective synthesis of ester derivatives with weak and strong bases in quantitative yields. Allyl alcohol was used as self and cross-metathesis substrate for the HG2 catalyzed sequential cross-metathesis/dehydrogenative alcohol coupling reactions to obtain γ-butyrolactone and long-chain ester derivatives in quantitative yields.
- ?zer, Halenur,Arslan, Dilan,?ztürk, Bengi ?zgün
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p. 5992 - 6000
(2021/04/12)
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- Understanding Ligand-Directed Heterogeneous Catalysis: When the Dynamically Changing Nature of the Ligand Layer Controls the Hydrogenation Selectivity
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We present a mechanistic study on the formation and dynamic changes of a ligand-based heterogeneous Pd catalyst for chemoselective hydrogenation of α,β-unsaturated aldehyde acrolein. Deposition of allyl cyanide as a precursor of a ligand layer renders Pd highly active and close to 100 % selective toward propenol formation by promoting acrolein adsorption in a desired configuration via the C=O end. Employing a combination of real-space microscopic and in-operando spectroscopic surface-sensitive techniques, we show that an ordered active ligand layer is formed under operational conditions, consisting of stable N-butylimine species. In a competing process, unstable amine species evolve on the surface, which desorb in the course of the reaction. Obtained atomistic-level insights into the formation and dynamic evolution of the active ligand layer under operational conditions provide important input required for controlling chemoselectivity by purposeful surface functionalization.
- Baumann, Ann-Katrin,Haugg, Philipp A.,Schauermann, Swetlana,Schmidt, Marvin C.,Schr?der, Carsten,Smyczek, Jan
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p. 16349 - 16354
(2021/06/25)
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- Preparation method of allyl alcohol
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The invention provides a preparation method of allyl alcohol. The preparation method of allyl alcohol comprises the following steps: reacting propylene carbonate monomers under the action of a catalyst to generate allyl alcohol, the catalyst is selected from one or more of a Lewis basic catalyst, a Lewis acidic catalyst and a transesterification catalyst; the Lewis basic catalyst is selected from one or more of sylvite, a nitrogen heterocyclic compound and an amino-containing compound; the Lewis acid catalyst is one or more of a metal salt, a metal complex and a boron-based complex, wherein the metal is selected from Sn, Zn, Al or Mg; the ester exchange catalyst is one or more of organic tin and organic titanium. According to the preparation method provided by the invention, allyl alcohol can be obtained by a one-step method under a relatively mild condition, so that the preparation process is greatly simplified, the condition requirement is reduced, and good product yield is ensured.
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Paragraph 0058-0081
(2021/11/21)
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- N,N,O-Coordinated tricarbonylrhenium precatalysts for the aerobic deoxydehydration of diols and polyols
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Rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using L4Re(CO)3as precatalyst (L4Re(CO)3= tricarbonylrhenium 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)phenolate). The DODH reaction was optimized using 2 mol% of L4Re(CO)3as precatalyst and 3-octanol as both reductant and solvent under aerobic conditions, generating the active high-valent rhenium speciesin situ. Both diol and biomass-based polyol substrates could be applied in this system to form the corresponding olefins with moderate to high yield. Typical features of this aerobic DODH system include a low tendency for the isomerization of aliphatic external olefin products to internal olefins, a high butadiene selectivity in the DODH of erythritol, the preferential formation of 2-vinylfuran from sugar substrates, and an overall low precatalyst loading. Several of these features indicate the formation of an active species that is different from the species formed in DODH by rhenium-trioxo catalysts. Overall, the bench-top stable and synthetically easily accessible, low-valent NNO-rhenium complex L4Re(CO)3represents an interesting alternative to high-valent rhenium catalysts in DODH chemistry.
- Klein Gebbink, Robertus J. M.,Li, Jing,Lutz, Martin
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p. 3782 - 3788
(2020/06/22)
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- Nickel-Catalyzed Asymmetric Reductive 1,2-Carboamination of Unactivated Alkenes
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Starting from diverse alkene-tethered aryl iodides and O-benzoyl-hydroxylamines, the enantioselective reductive cross-electrophilic 1,2-carboamination of unactivated alkenes was achieved using a chiral pyrox/nickel complex as the catalyst. This mild, modular, and practical protocol provides rapid access to a variety of β-chiral amines with an enantioenriched aryl-substituted quaternary carbon center in good yields and with excellent enantioselectivities. This process reveals a complementary regioselectivity when compared to Pd and Cu catalysis.
- He, Jun,Xue, Yuhang,Han, Bo,Zhang, Chunzhu,Wang, You,Zhu, Shaolin
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supporting information
p. 2328 - 2332
(2020/01/08)
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- Regulating Hydrogenation Chemoselectivity of α,β-Unsaturated Aldehydes by Combination of Transfer and Catalytic Hydrogenation
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Two hydrogenation mechanisms, transfer and catalytic hydrogenation, were combined to achieve higher regulation of hydrogenation chemoselectivity of cinnamyl aldehydes. Transfer hydrogenation with ammonia borane exclusively reduced C=O bonds to get cinnamyl alcohol, and Pt-loaded metal–organic layers efficiently hydrogenated C=C bonds to synthesize phenyl propanol with almost 100 % conversion rate. The hydrogenation could be performed under mild conditions without external high-pressure hydrogen and was applicable to various α,β-unsaturated aldehydes.
- Zhou, Yangyang,Li, Zihao,Liu, Yanbo,Huo, Jia,Chen, Chen,Li, Qiling,Niu, Songyang,Wang, Shuangyin
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p. 1746 - 1750
(2020/02/25)
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- Piperazine-promoted gold-catalyzed hydrogenation: The influence of capping ligands
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Gold nanoparticles (NPs) combined with Lewis bases, such as piperazine, were found to perform selective hydrogenation reactions via the heterolytic cleavage of H2. Since gold nanoparticles can be prepared by many different methodologies and using different capping ligands, in this study, we investigated the influence of capping ligands adsorbed on gold surfaces on the formation of the gold-ligand interface. Citrate (Citr), poly(vinyl alcohol) (PVA), polyvinylpyrrolidone (PVP), and oleylamine (Oley)-stabilized Au NPs were not activated by piperazine for the hydrogenation of alkynes, but the catalytic activity was greatly enhanced after removing the capping ligands from the gold surface by calcination at 400 °C and the subsequent adsorption of piperazine. Therefore, the capping ligand can limit the catalytic activity if not carefully removed, demonstrating the need of a cleaner surface for a ligand-metal cooperative effect in the activation of H2 for selective semihydrogenation of various alkynes under mild reaction conditions.
- Barbosa, Eduardo C. M.,Camargo, Pedro H. C.,Fiorio, Jhonatan L.,Hashmi, A. Stephen K.,Kikuchi, Danielle K.,Rossi, Liane M.,Rudolph, Matthias
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p. 1996 - 2003
(2020/04/22)
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- Reduction of carbon dioxide at a plasmonically active copper-silver cathode
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Electrochemically deposited copper nanostructures were coated with silver to create a plasmonically active cathode for carbon dioxide (CO2) reduction. Illumination with 365 nm light, close to the peak plasmon resonance of silver, selectively enhanced 5 of the 14 typically observed copper CO2 reduction products while simultaneously suppressing hydrogen evolution. At low overpotentials, carbon monoxide was promoted in the light and at high overpotentials ethylene, methane, formate, and allyl alcohol were enhanced upon illumination; generally C1 products and C2/C3 products containing a double carbon bond were selectively promoted under illumination. Temperature-dependent product analysis in the dark showed that local heating is not the cause of these selectivity changes. While the exact plasmonic mechanism is still unknown, these results demonstrate the potential for enhancing CO2 reduction selectivity at copper electrodes using plasmonics.
- Corson, Elizabeth R.,Subramani, Ananya,Cooper, Jason K.,Kostecki, Robert,Urban, Jeffrey J.,McCloskey, Bryan D.
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supporting information
p. 9970 - 9973
(2020/09/23)
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- Olefin reaction in the catalyst and the olefin production
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PROBLEM TO BE SOLVED: To provide a catalyst for obtaining an olefin in high selectivity with a vicinal diol as a raw material.SOLUTION: A catalyst for olefination reaction for use in a reaction to produce an olefin by a reaction of a polyol, having two adjacent carbon atoms each having a hydroxy group, with hydrogen comprises: a carrier; at least one oxide selected from the group consisting of oxides of the group 6 elements and oxides of the group 7 elements supported on the carrier; and at least one metal selected from the group consisting of silver, iridium, and gold supported on the carrier.SELECTED DRAWING: None
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Paragraph 0141-0143; 0145; 0149-0150
(2020/10/31)
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- Ouabain 19-site primary hydroxyl derivative as well as preparation method and application thereof
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The invention provides an ouabain 19-site primary hydroxyl derivative as well as a preparation method and application thereof. The structure of the ouabain 19-site primary hydroxyl derivative is shownas a formula I. The derivative has very low toxicity to normal cells and also has an excellent effect of inhibiting tumor cells. In addition, the derivative can effectively inhibit tumor cell migration and invasion. Therefore, the ouabain 19-site primary hydroxyl derivative has a very good application prospect in preparation of drugs for resisting tumors and inhibiting tumor invasion and/or migration.
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Paragraph 0063-0067
(2020/12/05)
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- Enhanced activity for gas phase propylene oxide rearrangement to allyl alcohol by Au promotion of Li3PO4 catalyst
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In present paper, lithium phosphate (Li3PO4) promoted by nano-gold (denoted as Au/Li3PO4) was used in gas phase propylene oxide (PO) rearrangement to produce allyl alcohol (AA). It was found that the support of gold could improve the catalytic activity as compared with pure Li3PO4. Au/Li3PO4 with gold loading of 0.042 wt% showed higher catalytic performance. The enhancement might come from the increase of the strength and amount of strong basic sites after gold deposition. Results of XPS spectra and density functional theory (DFT) verified that the charge transfer from oxygen species to gold species led to the electron-rich gold species, which acted as stronger base sites.
- Zhu, Xiangshuai,Wang, Dongyu,Li, Zhishan,Ma, Weihua
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- Method of zeolite-like imidazole metallic organic framework ZIFs for preparing alpha,beta-unsaturated alcohol through alpha,beta-unsaturated aldehyde hydrogenation
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The invention relates to a method of a zeolite-like imidazole metallic organic framework ZIFs for preparing alpha,beta-unsaturated alcohol through alpha,beta-unsaturated aldehyde hydrogenation. According to the method, a microwave synthesis method, a solvent heat method or a rapid stirring method is adopted to prepare a catalyst, namely the zeolite-like imidazole metallic organic framework ZIFs, the ZIFs can be directly adopted to prepare alpha,beta-unsaturated alcohol through alpha,beta-unsaturated aldehyde hydrogenation, and compared with a conventional non-noble metal catalyst, the catalystis capable of greatly increasing the conversion rate of cinnamyl aldehyde and improving selectivity of the cinnamyl aldehyde, and compared with a loaded type catalyst, the catalyst is simple in preparation procedure and low in cost.
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Paragraph 0016; 0020; 0022; 0026
(2019/05/08)
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- CeO2 promoting allyl alcohol synthesis from glycerol direct conversion over MoFe/CeO2 oxide catalysts: morphology and particle sizes dependent
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MoFe-N, MoFe/c–CeO2, MoFe/p1–CeO2, and MoFe/p2–CeO2 (where N, c, and p stand for non-supported, nanocube, and nanoparticle) oxide catalysts were designed for gas-glycerol direct catalytic conversion into allyl alcohol. The catalysts also were characterized by XRD, TEM, BET, H2-TPR, and NH3-TPD. Mo–Fe oxides were highly dispersed on the surface of c-CeO2 and p-CeO2 supports, different with the MoFe-N consist of crystalline Fe2(MoO4)3 and Fe2O3 crystalline phase. The support effect and special natural property of CeO2 significantly improve the allyl alcohol selectivity from gas-glycerol over MoFe/CeO2. The p-CeO2 with low particle sizes and crystalline degree was superior to high-crystalline nanocube c-CeO2 to promote its interaction with the MoFe oxide active components, and improve the surface acid site concentration and reducibility of MoFe/CeO2 as well as catalytic activity and stability for allyl alcohol synthesis from gas-glycerol without any extra hydrogen donors. Over the MoFe/p2–CeO2, the glycerol conversion reached 97.1%, and the selectivity of allyl alcohol, enthanal, propanoic acid, and acrylic acid were 23.3%, 8.6%, 12.6%, and 7.8%, respectively, yielding allyl alcohol of 22.6%.
- Lan, Hai,Zeng, Jia,Zhang, Biao,Jiang, Yi
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p. 1565 - 1580
(2018/12/13)
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- New insights for the valorisation of glycerol over MgO catalysts in the gas-phase
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Aqueous glycerol solutions of up to 50 wt% were reacted over magnesium oxide catalysts at temperatures greater than 300 °C, the reactivity of which was compared to catalyst-free reactions. Under catalyst-free conditions, modest levels of dehydration to hydroxyacetone were observed at temperatures >400 °C in a steel reactor tube and >320 °C over silicon carbide. For reactions over MgO, the product distribution becomes more diverse, resulting in the formation of methanol, acetaldehyde, ethylene glycol, 1,2-propanediol and acetic acid. The methanol space-time-yield over MgO catalyst samples (0.5 g) was found to be highest at 400 °C (205 g h-1 kgcat-1) with a 50 wt% solution of glycerol, or with a glycerol concentration of 10 wt%; 255 g h-1 kgcat-1 over 0.1 g of catalyst. Despite the high glycerol conversion achieved, the MgO catalyst was found to be stable over 48 h, following a modest decrease in glycerol conversion during the initial 2 h of reaction. Post-reaction characterisation revealed that the level of coking at high glycerol conversions (>90%) was ≥120 mg gcat-1. The carbon mass balance determined by GC analysis for a typical reaction was 75% and so the carbon lost from catalyst coking only represents a modest quantity of the missing carbon; typically 10%. MgO was also found to promote the formation of high molecular weight products via condensation reactions, which were responsible for the remainder of the missing carbon; ca. 15%. Therefore, the total organic content of the post-reaction mixture and coke was calculated to be 94% of the starting solution. We conclude that the catalyst surface directs the formation of methanol, however, the results indicate that the reaction conditions are crucial to obtain optimum yields.
- Smith, Louise R.,Smith, Paul J.,Mugford, Karl S.,Douthwaite, Mark,Dummer, Nicholas F.,Willock, David J.,Howard, Mark,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 1464 - 1475
(2019/03/26)
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- A study of the oxidehydration of 1,2-propanediol to propanoic acid with bifunctional catalysts
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The gas-phase oxidehydration (ODH) of 1,2-propanediol to propionic acid has been studied as an intermediate step in the multi-step transformation of bio-sourced glycerol into methylmethacrylate. The reaction involves the dehydration of 1,2-propanediol into propionaldehyde, which occurs in the presence of acid active sites, and a second step of oxidation of the aldehyde to the carboxylic acid. The two reactions were carried out using a cascade strategy and multifunctional catalysts, made of W-Nb-O, W-V-O and W-Mo-V-O hexagonal tungsten bronzes, the same systems which are also active and selective in the ODH of glycerol into acrylic acid. Despite the similarities of reactions involved, the ODH of 1,2-propanediol turned out to be less selective than glycerol ODH, with best yield to propanoic acid no higher than 13percent, mainly because of the parallel reaction of oxidative cleavage, occurring on the reactant itself, which led to the formation of C1-C2 compounds.
- Bandinelli, Claudia,Basile, Francesco,Cavani, Fabrizio,Concepcion, Patricia,De Maron, Jacopo,Dimitratos, Nikolaos,Lambiase, Barbara,Nieto, Jose Manuel Lopez,Tabanelli, Tommaso
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- A Cptt-Based Trioxo-Rhenium Catalyst for the Deoxydehydration of Diols and Polyols
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Trioxo-rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using CpttReO3 as a new catalyst (Cptt=1,3-di-tert-butylcyclopentadienyl). The DODH reaction was optimized using 2 mol % of CpttReO3 and 3-octanol as both reductant and solvent. The CpttReO3 catalyst exhibits an excellent activity for biomass-derived polyols. Specifically, glycerol is almost quantitatively converted to allyl alcohol and mucic acid gives 75 % of muconates at 91 % conversion. In addition, the loading of CpttReO3 can be reduced to 0.1 mol % to achieve a turn-over number as high as 900 per Re when using glycerol as substrate. Examination of DODH reaction profiles by NMR spectroscopy indicates that catalysis is related to Cp-ligand release, which raises questions on the nature of the actual catalyst.
- Li, Jing,Lutz, Martin,Otte, Matthias,Klein Gebbink, Robertus J. M.
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p. 4755 - 4760
(2018/10/02)
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- Vanadium-Catalyzed Deoxydehydration of Glycerol Without an External Reductant
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A vanadium-catalysed deoxydehydration (DODH) of neat glycerol has been developed. Cheap and readily available ammonium metavanadate (NH4VO3) affords higher yields of allyl alcohol than the well-established catalyst methyltrioxorhenium. A study in which deuterium-labelled glycerol was used was undertaken to further elucidate the dual role of glycerol as both an oxidant and reductant. This study led to the proposal of a metal-catalysed DODH mechanism for the production of allyl alcohol and a deeper understanding of the formation of the byproducts acrolein and propanal.
- Petersen, Allan R.,Nielsen, Lasse B.,Dethlefsen, Johannes R.,Fristrup, Peter
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p. 769 - 778
(2018/02/27)
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- PROCESS FOR THE PRODUCTION OF ALLYL COMPOUNDS BY DEOXYDEHYDRATION OF GLYCEROL
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The present invention concerns acontinuous-flow process for the production of allyl compounds by deoxydehydration of glycerol comprising the following steps: (a)Forming a reactive solution by mixing glycerol (1) with: ?a carboxylic acid (2), and/or ?a triethyl orthoester, preferably triethyl orthoformate (TEOF); (b)Feeding the reactive solution to an inlet of a channel of a thermolysis microreactor module wherein the channel has an inner hydraulic diameter, D=4A/P, wherein A is the area and P the perimeter of a cross-section of the channel, of not more than 1000μm, (c)Exposing the reactive solution to thermolysis by driving a flow of the reactive solution along the channel from the inlet to an outlet, for a thermolysis time, t, at a pressure, P, and at a thermolysis temperature, T, larger than 200°C, to form thermolysis products including at least one allyl compound; and Recovering the thermolysis products at the outlet and separating the at least one allyl compound from the other thermolysis products
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Paragraph 0059
(2018/09/20)
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- Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
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Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
- Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
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p. 3516 - 3524
(2018/04/14)
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- Ruthenium(II)-Catalyzed Regio- and Stereoselective C-H Allylation of Indoles with Allyl Alcohols
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A ruthenium-catalyzed C-H allylation of indoles with allyl alcohols via β-hydroxide elimination is reported. Without external oxidants and expensive additives, this reaction features mild reaction conditions, compatibility with various functional groups, and good to excellent regioselectivity and stereoselectivity.
- Wu, Xiaowei,Ji, Haitao
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supporting information
p. 2224 - 2227
(2018/04/30)
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- PROCESS FOR PRODUCTION OF ALLYL ALCOHOL
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The invention relates to a process for producing allyl alcohol, the process comprising: dehydrating a C3-oxygenate comprising monopropylene glycol or 1,3-propanediol; wherein the dehydration is performed in the presence of a basic catalyst. The C3-oxygenate may be derived from a biomass conversion process and subsequently converted to acrylic acid.
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Page/Page column 14; 15
(2018/06/16)
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- Exploring the Reaction Pathways of Bioglycerol Hydrodeoxygenation to Propene over Molybdena-Based Catalysts
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The one-step reaction of glycerol with hydrogen to form propene selectively is a particularly challenging catalytic pathway that has not yet been explored thoroughly. Molybdena-based catalysts are active and selective to C?O bond scission; propene is the only product in the gas phase under the standard reaction conditions, and further hydrogenation to propane is impeded. Within this context, this work focuses on the exploration of the reaction pathways and the investigation of various parameters that affect the catalytic performance, such as the role of hydrogen on the product distribution and the effect of the catalyst pretreatment step. Under a hydrogen atmosphere, propene is produced primarily via 2-propenol, whereas under an inert atmosphere propanal and glycerol dissociation products are formed mainly. The reaction most likely proceeds through a reverse Mars–van Krevelen mechanism as partially reduced Mo species drive the reaction to the formation of the desired product.
- Zacharopoulou, Vasiliki,Vasiliadou, Efterpi S.,Lemonidou, Angeliki A.
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p. 264 - 275
(2017/12/15)
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- Acrolein production by gas-phase glycerol dehydration using PO4/Nb2O5 catalysts
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In this study, modified niobium oxide were prepared to study the addictive effects on the catalytic performance for gas-phase glycerol dehydration. The catalysts were characterized by N2 adsorption/desorption, XRD, NH3-TPD, FT-IR. The amount of phosphoric acid was up to 50 wt% in niobium. As a result, the highest glycerol conversion was achieved over 20 wt% PO4/Nb2O5. It indicates that the optimal amount of phosphoric acid leads the catalyst to have appropriate acidity which is an important factor for gas-phase glycerol dehydration.
- Lee, Kyu Am,Ryoo, HeeKyoung,Ma, Byung Chol,Kim, Youngchul
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p. 1312 - 1315
(2017/12/15)
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- Gas phase dehydration of glycerol to acrolein on an amino siloxane-functionalized MCM-41 supported Wells-Dawson type H6P2W18O62 catalyst
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A novel amino siloxane-functionalized MCM-41 supported Wells-Dawson type H6P2W18O62 (D-HPW) catalyst was synthesized by a two-step method and investigated in the gas phase dehydration of glycerol to acrolein. The amino siloxanes (KH-540, KH-792, and NQ-62) were firstly loaded on MCM-41, and then D-HPW was impregnated. After loading of amino siloxanes, the heteropolyanions interacted with the amine groups, generating strongly distorted heteropolyanions on the surface of the host materials. As a result, these heteropolyanions with a highly deformed structure might render H+ more active, finally showing more Br?nsted acid sites. The strong chemical interaction between the amine groups and the D-HPW molecules was strengthened with the increase in the number of amine groups. The results showed that the acrolein selectivity was enhanced after loading of amino siloxanes because of the increased Br?nsted acid sites. The catalyst stability was enhanced, because the amount of coke decreased, and the enhancement of the interaction between the -NH2 groups in the amino siloxane and the D-HPW molecules prevented the leaching of D-HPW. Finally, D-HPW/NQ-62-MCM-41 exhibited the highest acrolein selectivity and stability. The reaction pathway for the gas-phase dehydration of glycerol on the amino siloxane-functionalized MCM-41 supported D-HPW catalyst is also proposed.
- Ding, Jianfei,Ma, Tianlin,Shao, Rong,Xu, Wei,Wang, Pengfei,Song, Xiaoyong,Guan, Rongfeng,Yeung, Kinglun,Han, Wei
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p. 14271 - 14280
(2018/08/28)
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- Reactions of N-Allyl- and N-Propargyltriflimides with N,N′-Disubstituted Carbodiimides
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The alkylating activity of N-allyl- and N-propargyltriflimides toward N,N′-dicyclohexyl- and N,N′-diphenylcarbodiimides has been studied. Activation of the nitrogen atom by two electron-withdrawing trifluoromethanesulfonyl groups favors cleavage of the C–N bond in the absence of a catalyst with the formation of N-substituted unsaturated ureas.
- Tolstikova,Danilevich, Yu. S.,Shainyan
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p. 1103 - 1105
(2018/09/11)
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- On the direct use of CO2 in multicomponent reactions: Introducing the Passerini four component reaction
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We introduce a novel isocyanide-based multicomponent reaction, the Passerini four component reaction (P-4CR), by replacing the carboxylic acid component of a conventional Passerini three component reaction (P-3CR) with an alcohol and CO2. Key to this approach is the use of a switchable solvent system, allowing the synthesis of a variety of α-carbonate-amides. The reaction was first investigated and optimized using butanol, isobutyraldehyde, tert-butyl isocyanide and CO2. Parameters investigated included the effect of reactant equivalents, reactant concentration, solvent, catalyst, catalyst concentration and CO2 pressure. Of the other parameters, the purity of the aldehyde and its tendency to oxidize was one of the most critical parameters for a successful P-4CR. After optimization, a total of twelve (12) P-4CR compounds were synthesized with conversions ranging between 16 and 82% and isolated yields between 18 and 43%. Their structures were confirmed via1H and 13C NMR, FT-IR and high resolution mass spectrometry (ESI-MS). In addition, three (3) hydrolysis products of P-4CR (α-hydroxyl-amides) were successfully isolated with yields between 23 and 63% and fully characterized (1H, 13C NMR, FT-IR and ESI-MS) as well.
- Onwukamike, Kelechukwu Nnabuike,Grelier, Stéphane,Grau, Etienne,Cramail, Henri,Meier, Michael A. R.
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p. 31490 - 31495
(2018/09/25)
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- Electrochemical CO Reduction Builds Solvent Water into Oxygenate Products
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Numerous studies have examined the electrochemical reduction of CO (COR) to oxygenates (e.g., ethanol). None have considered the possibility that oxygen in the product might arise from water rather than from CO. To test this assumption, C16O reduction was performed in H218O electrolyte. Surprisingly, we found that 60-70% of the ethanol contained 18O, which must have originated from the solvent. We extended our previous all-solvent density functional theory metadynamics calculations to consider the possibility of incorporating water, and indeed, we found a new mechanism involving a Grotthuss chain of six water molecules in a concerted reaction with the?C-CH intermediate to form?CH-CH(18OH), subsequently leading to (18O)ethanol. This competes with the formation of ethylene that also arises from?C-CH. These unforeseen results suggest that all previous studies of COR under aqueous conditions must be reexamined.
- Lum, Yanwei,Cheng, Tao,Goddard, William A.,Ager, Joel W.
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supporting information
p. 9337 - 9340
(2018/07/25)
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- ALLYL ALCOHOL BY CATALYTIC ISOMERIZATION OF A PROPYLENE OXIDE STREAM
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Allyl alcohol production processes are generally described herein. One or more of the processes generally include contacting a propylene oxide stream with an isomerization catalyst under isomerization conditions sufficient to form an isomerization product stream including allyl alcohol, wherein the propylene oxide stream includes a total impurity concentration of at least 100 ppm. One or more of the processes generally includes purging at least a portion of a stream from one or more separation unit(s).
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Paragraph 0081-0083
(2017/06/12)
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- USE OF RHENIUM-CONTAINING SUPPORTED HETEROGENEOUS CATALYSTS FOR THE DIRECT DEOXYDEHYDRATION OF GLYCEROL TO ALLYL ALCOHOL
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The present invention relates to the use of rhenium-containing supported heterogeneous catalysts for the deoxydehydration of glycerol to allyl alcohol, as well as to a process for the production of allyl alcohol from glycerol, in the presence of such heterogeneous catalysts.
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Page/Page column 6; 9-10
(2017/02/24)
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- Deoxydehydration of vicinal diols and polyols catalyzed by pyridinium perrhenate salts
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Simple ammonium and pyridinium perrhenate salts were evaluated as catalysts for the deoxydehydration (DODH) of diols into alkenes. Pyridinium perrhenates were found to be effective catalysts at much lower temperatures than those in previous reports, outperforming primary, secondary, and tertiary ammonium salts, while quaternary ammonium salts are effectively inactive. The mechanism of reaction was studied computationally using DFT calculations which indicate that proton shuttling between the ion pair is intrinsic to the mechanism and that the reduction of rhenium by the phosphine occurs before the diol condensation.
- Morris, Danny S.,Van Rees, Karlotta,Curcio, Massimiliano,Cokoja, Mirza,Kühn, Fritz E.,Duarte, Fernanda,Love, Jason B.
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p. 5644 - 5649
(2017/12/07)
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- Acid-activated and WOx-loaded montmorillonite catalysts and their catalytic behaviors in glycerol dehydration
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The use of H2SO4-, HCl-, H3PO4-, and CH3COOH-activated montmorillonite (Mt) and WOx/H3PO4-activated Mt as catalysts for the gas-phase dehydration of glycerol was investigated. The WOx/H3PO4-activated Mt catalysts were prepared by an impregnation method using H3PO4-activated Mt (Mt-P) as the support. The catalysts were characterized using powder X-ray diffraction, Fourier-transform infrared spectroscopy, N2 adsorption-desorption, diffuse reflectance ultraviolet-visible spectroscopy, temperature-programmed desorption of NH3, and thermogravimetric analysis. The acid activation of Mt and WOx loaded on Mt-P affected the strength and number of acid sites arising from H+ exchange, the leaching of octahedral Al3+ cations from Mt octahedral sheets, and the types of WOx (2.7 ≤ x ≤ 3) species (i.e., isolated WO4/WO6-containing clusters, two-dimensional [WO6] polytungstates, or three-dimensional WO3 crystals). The strong acid sites were weakened, and the weak and medium acid sites were strengthened when the W loading on Mt-P was 12 wt% (12%W/Mt-P). The 12%W/Mt-P catalyst showed the highest catalytic activity. It gave a glycerol conversion of 89.6% and an acrolein selectivity of 81.8% at 320 °C. Coke deposition on the surface of the catalyst led to deactivation.
- Yu, Weihua,Wang, Pengpeng,Zhou, Chunhui,Zhao, Hanbin,Tong, Dongshen,Zhang, Hao,Yang, Huimin,Ji, Shengfu,Wang, Hao
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p. 1087 - 1100
(2017/06/23)
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- Intramolecular Chirality Transfer [2 + 2] Cycloadditions of Allenoates and Alkenes
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Intramolecular chirality transfer [2 + 2] cycloaddition of enantiomerically enriched allenoates and alkenes is presented. The use of a chiral catalyst was found to be critical to achieve high levels of diastereoselectivity compared to use of an achiral catalyst. The method developed leads to highly substituted cyclobutanes that would be difficult to prepare by alternative methods.
- Xu, Yao,Hong, Young J.,Tantillo, Dean J.,Brown, M. Kevin
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supporting information
p. 3703 - 3706
(2017/07/26)
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- Gold-Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H2 Heterolytic Activation by Frustrated Lewis Pairs
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The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom-ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity. (Graph Presented).
- Fiorio, Jhonatan L.,López, Núria,Rossi, Liane M.
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p. 2973 - 2980
(2017/05/31)
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- BiCl3: A versatile catalyst for the tetrahydropyranylation and depyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric diols
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Bismuth trichloride as mild reagent, has been found to be a worthful catalyst for tetrahydropyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric di-ols. At room temperature the reagent THP(3,4-dihydro-2H-pyran) was successfully employed as pyranylating agent in presence of BiCl3catalyst without the use of a solvent and the yields of the products were found to be 90-96%. Further, the depyranylation of alcohols was achieved in quantitative yield by simple addition of MeOH using the same catalyst. The developed method was showed good chemo-selectivity in symmetrical diols for mono THP protection.
- Vijaya Durga,Balamurali Krishna,Baby Ramana,Santha Kumari,Vijay,Hari Babu
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p. 1030 - 1034
(2017/05/26)
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- Manganese-Catalyzed Hydrogenation of Esters to Alcohols
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Homogeneous catalytic hydrogenation of esters to alcohols is an industrially important, environmentally benign reaction. While precious metal-based catalysts for this reaction are now well known, only very few catalysts based on first-row metal complexes were reported. Here we present the hydrogenation of esters catalyzed by a complex of earth-abundant manganese. The reaction proceeds under mild conditions and insight into the mechanism is provided based on an NMR study and the synthesis of novel Mn complexes postulated as intermediates.
- Espinosa-Jalapa, Noel Angel,Nerush, Alexander,Shimon, Linda J. W.,Leitus, Gregory,Avram, Liat,Ben-David, Yehoshoa,Milstein, David
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supporting information
p. 5934 - 5938
(2017/05/08)
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- MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
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The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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Paragraph 00352-00353
(2017/09/05)
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