123-73-9Relevant articles and documents
Rice,Fishbein
, p. 1005,1008 (1956)
Villani,Nord
, p. 1675 (1946)
Wertyporoch,Silber
, ()
Magnetic core-shell Fe3O4?Cu2O and Fe3O4?Cu2O-Cu materials as catalysts for aerobic oxidation of benzylic alcohols assisted by TEMPO and: N -methylimidazole
Liu, Xiaoming,Lu, Chunxin,Senthilkumar, Samuthirarajan,Shen, Zhongquan,Xu, Binyu,Zhong, Wei
, p. 26142 - 26150 (2020)
In this work, core-shell Fe3O4?Cu2O and Fe3O4?Cu2O-Cu nanomaterials for aerobic oxidation of benzylic alcohols are reported with 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) and N-methylimidazole (NMI) as the co-catalysts. To anchor Cu2O nanoparticles around the magnetic particles under solvothermal conditions, the magnetic material Fe3O4 was modified by grafting a layer of l-lysine (l-Lys) to introduce -NH2 groups at the surface of the magnetic particles. With amine groups as the anchor, Cu(NO3)2 was used to co-precipitate the desired Cu2O by using ethylene glycol as the reducing agent. Prolonging the reaction time would lead to over-reduced forms of the magnetic materials in the presence of copper, Fe3O4?Cu2O-Cu. The nanomaterials and its precursors were fully characterized by a variety of spectroscopic techniques. In combination with both TEMPO and NMI, these materials showed excellent catalytic activities in aerobic oxidation of benzylic alcohols under ambient conditions. For most of the benzylic alcohols, the conversion into aldehydes was nearly quantitative with aldehydes as the sole product. The materials were recyclable and robust. Up to 7 repeat runs, its activity dropped less than 10%. The over-reduced materials, Fe3O4?Cu2O-Cu, exhibited slightly better performance in durability. The magnetic properties allowed easy separation after reaction by simply applying an external magnet.
Supported bimetallic AuPd clusters using activated Au25 clusters
Lee, Kee Eun,Shivhare, Atal,Hu, Yongfeng,Scott, Robert W.J.
, p. 259 - 265 (2017)
Bimetallic AuPd nanoparticles on alumina supports were prepared using Au25(SR)18 precursors activated by mild calcination or LiBH4 treatment, followed by selective deposition of Pd via ascorbic acid reduction. Comparison of their catalytic activity for the oxidation of crotyl alcohol showed that bimetallic structure had significantly improved catalysis compared to Pd/Al2O3. In particular, AuPd samples grown from LiBH4-activated Au25 clusters exhibit the highest catalytic activity as well as high selectivity towards crotonaldehyde formation, likely due to their smaller particle sizes as compared to AuPd samples grown from calcined Au25 clusters. X-ray absorption spectroscopy (XAS) at the Au L3-edge, Pd L3-edge and Pd K-edges showed that the resulting bimetallic AuPd nanoparticles had Au-Pd core-shell structures with a 4d-electron poor Pd surface.
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Halpern et al.
, p. 4097 (1961)
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Selective oxidation of crotyl alcohol by Au: X Pd bimetallic pseudo-single-atom catalysts
Chivers, Brandon A.,Scott, Robert W. J.
, p. 7706 - 7718 (2020)
AuPd bimetallic single-atom catalysts are being extensively studied as selective catalysts for hydrogenation and oxidation reactions due to their high selectivity. Previous work in our group has shown that alloy and core-shell AuPd nanoparticle catalysts can selectively oxidize crotyl alcohol to crotonaldehyde at room temperature in base-free conditions. In this work, we discuss the synthesis, extensive characterization, and activity for crotyl alcohol oxidation across a series of AuxPd catalysts (x = 4, 3, 2, and 1) made by both co-reduction and sequential reduction strategies, in order to examine whether single-atom systems can lead to improved activity and/or selectivity for this reaction. X-ray absorption spectroscopy data shows that both co-and sequentially-reduced Au4Pd catalysts have very small Pd-Pd coordination numbers, with values of 1.2 ± 0.3 and 1.6 ± 0.3, respectively, which indicates that they are closest to single-atom systems. The co-Au4Pd catalyst, with the lowest Pd-Pd CN, also exhibits the highest selectivity for the selective oxidation of crotyl alcohol to crotonaldehyde. We were further able to enhance the selectivity of the AuPd nanoparticle catalysts by incorporating vinyl acetate as a hydride scavenger. We show in this paper that dispersing Pd in a Au matrix can lead to very selective catalysts while also lowering the amount of Pd needed in the system.
Aldol Condensation of Acetaldehyde over Titania, Hydroxyapatite, and Magnesia
Young, Zachary D.,Hanspal, Sabra,Davis, Robert J.
, p. 3193 - 3202 (2016)
The kinetics of aldol condensation of acetaldehyde were studied over anatase titania (TiO2), hydroxyapatite (HAP), and magnesia (MgO). Reactions were carried out in a fixed-bed reactor with a total system pressure of 220 kPa at temperatures between 533 and 633 K and acetaldehyde partial pressures between 0.05 and 50 kPa. Crotonaldehyde was the only product observed over all three catalysts, and severe catalyst deactivation occurred at acetaldehyde partial pressures of 5 kPa or greater. The aldol condensation reaction over all three catalysts was first order at low acetaldehyde partial pressure and approached zero order at high acetaldehyde partial pressure. No kinetic isotope effect (KIE) was observed with fully deuterated acetaldehyde reacting over TiO2 or HAP, implying that C-H bond activation is not kinetically relevant. These measurements are consistent with a mechanism in which adsorption and desorption steps are kinetically significant during the reaction. Characterization of the catalysts by adsorption microcalorimetry of acetaldehyde and ethanol and diffuse reflectance Fourier transform infrared spectroscopy of adsorbed acetaldehyde, crotonaldehyde, and acetic acid revealed a very high reactivity of these catalysts, even at low temperatures.
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Miller et al.
, p. 2732,2735 (1950)
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Effect of the ZrO2 phase on the structure and behavior of supported Cu catalysts for ethanol conversion
Sato,Volanti,Meira,Damyanova,Longo,Bueno
, p. 1 - 17 (2013)
The effect of amorphous (am-), monoclinic (m-), and tetragonal (t-) ZrO2 phase on the physicochemical and catalytic properties of supported Cu catalysts for ethanol conversion was studied. The electronic parameters of Cu/ZrO2 were determined by in situ XAS, and the surface properties of Cu/ZrO2 were defined by XPS and DRIFTS of CO-adsorbed. The results demonstrated that the kind of ZrO2 phase plays a key role in the determination of structure and catalytic properties of Cu/ZrO 2 catalysts predetermined by the interface at Cu/ZrO2. The electron transfer between support and Cu surface, caused by the oxygen vacancies at m-ZrO2 and am-ZrO2, is responsible for the active sites for acetaldehyde and ethyl acetate formation. The highest selectivity to ethyl acetate for Cu/m-ZrO2 catalyst up to 513 K was caused by the optimal ratio of Cu0/Cu+ species and the high density of basic sites (O2-) associated with the oxygen mobility from the bulk m-ZrO2.
Dual Role of the Rhodium(III) Catalyst in C-H Activation: [4 + 3] Annulation of Amide with Allylic Alcohols to 7-Membered Lactams
Sherikar, Mahadev Sharanappa,Devarajappa, Ravi,Prabhu, Kandikere Ramaiah
, p. 4625 - 4637 (2021)
[4 + 3] annulation of primary and secondary benzamide and cinnamamide derivatives using allyl alcohol as a coupling partner catalyzed by Rh(III) is reported, where Rh(III) is playing a dual role of an oxidant and a catalyst for C-H activation. The Rh-catalyst oxidizes allyl alcohol to its carbonyl derivative, and the in situ-generated carbonyl compound reacts with benzamide in the presence of the Rh-catalyst, forming the corresponding alkylated products. Mechanistic studies show that AgSbF6 is also playing a dual role. Apart from being a halide scavenger, AgSbF6 catalyzes the cyclization of the alkylated product, forming the desired lactam. The current method has good synthetic application and is useful for synthesizing a few biologically active compounds that can act as the dopamine D3 receptor ligand, including berberine-like analogues. The deuteration study and control experiments helped us to propose the mechanism.
Selective Oxidation of Allylic and Benzylic Alcohols Using Potassium Ruthenate (K2RuO4) Under Phase-Transfer Catalysis Conditions
Kim, Kwan Soo,Kim, Sung Jung,Song, Yang Heon,Hahn, Chi Sun
, p. 1017 - 1018 (1987)
Catalytic amounts of potassium ruthenate in the presence of potassium peroxodisulfate, which quickly regenerates ruthenate during reaction, selectively oxidize allylic and benzylic alcohols in the presence of Adogen 464 as phase-transfer catalyst at room temperature but do not affect saturated alcohols.
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Thomas,Warburton
, p. 2988 (1965)
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Systematic Screening for Catalytic Promiscuity in 4-Oxalocrotonate Tautomerase: Enamine Formation and Aldolase Activity
Zandvoort, Ellen,Baas, Bert-Jan,Quax, Wim J.,Poelarends, Gerrit J.
, p. 602 - 609 (2011)
The enzyme 4-oxalocrotonate tautomerase (4-OT) is part of a catabolic pathway for aromatic hydrocarbons in Pseudomonas putida mt-2, where it catalyzes the conversion of 2-hydroxy-2,4-hexadienedioate (1) to 2-oxo-3-hexenedioate (2). 4-OT is a member of the tautomerase superfamily, a group of homologous proteins that are characterized by a β-α-β structural fold and a catalytic amino-terminal proline. In the mechanism of 4-OT, Pro1 is a general base that abstracts the 2-hydroxyl proton of 1 for delivery to the C-5 position to yield 2. Here, 4-OT was explored for nucleophilic catalysis based on the mechanistic reasoning that its Pro1 residue has the correct protonation state (pKa～6.4) to be able to act as a nucleophile at pH 7.3. By using inhibition studies and mass spectrometry experiments it was first demonstrated that 4-OT can use Pro1 as a nucleophile to form an imine/enamine with various aldehyde and ketone compounds. The chemical potential of the smallest enamine (generated from acetaldehyde) was then explored for further reactions by using a small set of selected electrophiles. This systematic screening approach led to the discovery of a new promiscuous activity in wild-type 4-OT: the enzyme catalyzes the aldol condensation of acetaldehyde with benzaldehyde to form cinnamaldehyde. This low-level aldolase activity can be improved 16-fold with a single point mutation (L8R) in 4-OT's active site. The proposed mechanism of the reaction mimicks that used by natural class-I aldolases and designed catalytic aldolase antibodies. An important difference, however, is that these natural and designed aldolases use the primary amine of a lysine residue to form enamines with carbonyl substrates, whereas 4-OT uses the secondary amine of an active-site proline as the nucleophile catalyst. Further systematic screening of 4-OT and related proline-based biocatalysts might prove to be a useful approach to discover new promiscuous carbonyl transformation activities that could be exploited to develop new biocatalysts for carbon-carbon bond formation. Prozymes: A systematic screening strategy to discover new promiscuous carbonyl-transformation activities in 4oxalocrotonate tautomerase (4-OT) is reported. The N-terminal proline of this enzyme provides a chemical functionality in the active site that might be suitable for enamine catalysis. It is shown that the aldol condensation of acetaldehyde with benzaldehyde is catalyzed by 4-OT.
Pd nanoparticles supported on 1H-benzotriazole functionalized carbon with enhanced catalytic performance towards ethanol oxidation
Liu, Yanqin,Wang, Wei,Yang, Yan,Wang, Fengxia,Zhao, Xiaolong,Lei, Ziqiang
, p. 410 - 415 (2015)
Nitrogen functionalized carbon has received widely research interest because of their remarkable performance. In this paper, 1H-benzotriazole functionalized carbon (BTA-C) is fabricated and used as support to immobilize Pd nanoparticles. The physical characterization results demonstrate that the Pd nanoparticles uniformly disperse on the BTA-C. Because of the good effect of BTA functionalization, the as-prepared Pd/BTA-C catalyst has larger electrochemically active surface area contrasted to Pd/C. Meanwhile, the electrochemical test results indicate that the Pd/BTA-C possesses higher activity (more than 1.8 times), lower onset potential (negative 90 mV) and better stability than that of Pd/C counterpart in ethanol oxidation reaction. All results imply that the Pd/BTA-C is a promising candidate electrocatalyst in direct ethanol fuel cells.
Allen,Ball,Young
, p. 169 (1933)
Aerobic Oxidation of Alcohols Catalysed by Cu(I)/NMI/TEMPO System and Its Mechanistic Insights
Liu, Zhenzhen,Shen, Zhongquan,Zhang, Ning,Zhong, Wei,Liu, Xiaoming
, p. 2709 - 2718 (2018)
Abstract: Homogeneous Cu(I)/NMI/TEMPO catalyst system (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) has been investigated for its catalysis on the aerobic oxidation of 1-octanol and other alcohols into aldehydes under room temperature. The catalytic species was found to be a Cu(I) centre coordinated by two NMI molecules and other two weakly bound solvent molecules, [Cu(NMI)2(Sol)2]+ (Sol = solvent). When CuI was used, this species could be [Cu(NMI)I(Sol)2]. Not like being speculated previously, NMI in this system acts solely as a ligand and its role coordinated to the copper centre enhanced the electron density on the metal centre which promoted the O2 binding in the catalysis. The labile solvent binding to the Cu(I) centre is essential to ensure both oxygen and substrate binding. The catalyst system is suitable for the oxidation of various alcohols using a simple reaction setup and workup. In particular, the system possesses strong oxidizing capability in quantitative conversion of benzylic alcohols regardless of the substituents on the phenyl ring and allylic alcohols into aldehydes. A plausible mechanism was also proposed for the catalysis. Graphical Abstract: The aerobic oxidation of primary alcohols at room temperature to corresponding aldehydes was achieved by the catalyst composed by Cu(I) and methyl imidazole (NMI) mediated by TEMPO in acetonitrile. The catalytic species is proposed to be such a Cu(I) complex that two of its four coordinating sites are occupied by a strong ligand(s) and the rest two are weakly bound by solvent molecules.[Figure not available: see fulltext.].
Oxidation of Allylic Alcohols by Means of Electrochemical Methodology. Novel Rearrangement of Prenol under Direct Anodic Oxidation Conditions
Maki, Shojiro,Konno, Katsuhiro,Takayama, Hiroaki
, p. 559 - 560 (1995)
Electrochemical oxidation of naturally occurring allylic alcohols is described.Under direct anodic oxidation conditions, prenol 1 was readily oxidized, followed by rearrangement presumably on the surface of the anodic electrode, to give 3-hydroxy-2,2'-dimethyl-1,1'-dimethoxy propane 2 in high yield, whereas geraniol 5 afforded citral 6 under the same conditions.
A comparative study of Bi2WO6, CeO2, and TiO2 as catalysts for selective photo-oxidation of alcohols to carbonyl compounds
López-Tenllado,Murcia-López,Gómez,Marinas,Marinas,Urbano,Navío,Hidalgo,Gatica
, p. 375 - 381 (2015)
Several semiconductors based on ceria or bismuth tungstate were tested for selective oxidation of alcohols to carbonyl compounds in a search for photocatalysts more selective than TiO2. Gas-phase selective photo-oxidation of propan-2-ol to acetone and liquid-phase transformation of 2-buten-1-ol (crotyl alcohol) to 2-butenal (crotonaldehyde) were studied as test reactions. In both processes the highest selectivities were achieved with Bi2WO6-based solids. Further studies on crotyl alcohol transformation evidenced the lower adsorption of the aldehyde on these systems which could minimize the decrease in crotyl alcohol yield observed for TiO2 or CeO2 at high conversions. Incorporation of titania (5% molar) to the Bi2WO6 system increased the reaction rate significantly whereas the aldehyde yield remained high.
Effect of Cu content on the surface and catalytic properties of Cu/ZrO 2 catalyst for ethanol dehydrogenation
Freitas,Damyanova,Oliveira,Marques,Bueno
, p. 26 - 37 (2014)
ZrO2-supported Cu catalysts with different Cu content (5-30 wt.%) were prepared by impregnation method. The effect of Cu content on the structure, surface and catalytic properties of Cu/ZrO2 catalysts in the reaction of ethanol conversion was studied. The physicochemical characterization of the calcined and reduced samples was carried out by: N 2 adsorption-desorption isotherms, N2O titration, XRD, XPS, TPR and DRFTS of CO adsorption. It was observed that the increase of Cu content leads to decrease of the apparent copper metal dispersion caused by the strong agglomeration of the metal particles. The selectivity to different reaction products was connected with the electronic properties of the catalysts defined by the copper particle size and the interface at metal-oxide support. The highest selectivity to ethyl acetate over samples with Cu content ≥10 wt.% was assigned to the high density of basic sites of O2- ions and more heterogeneous distribution of copper species (Cu0/Cu +) defined by DRIFTS of CO adsorption and XPS.
A rational design of a Pd-based catalyst with a metal-metal oxide interface influencing molecular oxygen in the aerobic oxidation of alcohols
Meher, Songhita,Rana, Rohit Kumar
, p. 2494 - 2503 (2019)
In a green process for selective oxidation of alcohols, the utilization of molecular oxygen as a primary oxidant is the most critical step. Although many palladium (Pd)-based catalysts have shown potential, the role of different Pd-species in the aerobic oxidation reaction is still a matter of discussion. There have been diverse reports, which describe either Pd0 or Pd2+ as the individual species responsible for the aerobic oxidation of alcohols. Herein we demonstrate that the presence of both Pd0 and Pd2+ species with a Pd-PdO interface stabilized on the surface of reduced graphene oxide (rGO) is important for the oxidation of alcohols. With an optimum Pd2+/Pd0 ratio, the catalyst catalyzes the oxidation of benzyl alcohol in water with oxygen, resulting in a turnover frequency (TOF) of up to 18 000 h-1 with 98% selectivity towards the aldehyde. It is proposed that both metallic Pd and its oxide domains, when co-existing with a phase boundary between them, promote the activation of oxygen. On the other hand, rGO provides surface functionalities for the formation and stabilization of Pd-PdO nanoclusters enabling the catalyst to be both stable and reusable. Using histidine as a scavenger for singlet oxygen, we have also determined the importance of oxygen-activation in the reaction. Furthermore, the catalyst is capable of converting various other alcohols into the corresponding carbonyl compounds. Comparison of various catalysts shows that the Pd-PdO@rGO catalyst is the most efficient in terms of TOF, conversion and selectivity for the oxidation of benzyl alcohol using oxygen compared to the reported Pd-based catalysts, particularly when performed under milder reaction conditions. Therefore, the result on Pd-catalyst designing is believed to be of significance for the further developments in the environmentally benign oxidation processes involving molecular oxygen as the oxidant.
Ferritin-supported palladium nanoclusters: Selective catalysts for aerobic oxidations in water
Kanbak-Aksu,Nahid Hasan,Hagen,Hollmann,Sordi,Sheldon,Arends
, p. 5745 - 5747 (2012)
Confinement of nanometallic Pd within the core of a hyperthermophilic ferritin cage (from Pyrococcus furiosus) is reported. The resulting nanostructured hybrid catalysts can be used for highly specific aerobic oxidation of alcohols in water. This journal is
An experimental (flash vacuum pyrolysis) and theoretical study of the tautomerism of pyrazolinones at high temperatures
Yranzo, Gloria I.,Moyano, Elizabeth L.,Rozas, Isabel,Dardonville, Christophe,Elguero, Jose
, p. 211 - 216 (1999)
Flash vacuum pyrolysis experiments were carried out between 500 and 800°C on 3(5)-phenyl- and 3(5)-methylpyrazolinones and on 3(5)-methoxy-5(3)-phenylpyrazole. The origin of the isolated products (mainly indanone, hydroxyalkynes and α,β-unsaturated aldehydes) can be explained as arising from the hydroxy tautomers of pyrazolinones. Temperature effects on the tautomeric equilibrium of 1-phenyl-3-methylpyrazolinone in solution show that the percentage of the CH tautomer increases with the temperature. MP2 ab initio calculations on the model compound, pyrazolinone itself, have been used to rationalize these findings. The problem of the aromaticity of the four tautomers of pyrazolinone has been examined through Schleyer's NICS (nuclear independent chemical shifts) calculations.
A kinetic and mechanistic study of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous Alkaline medium
Sharma, Priyamvada,Sailani, Riya,Meena, Anita,Khandelwal, Chandra Lata
, p. 295 - 300 (2020)
The kinetics and mechanism of the osmium(VIII)-catalysed oxidation of crotyl alcohol by hexacyanoferrate(III) in aqueous alkaline medium is studied. The role of the osmium(VIII) catalyst is delineated to account for the experimental observations. A plausible reaction mechanism is suggested. Activation parameters such as the energy and entropy of activation are evaluated by employing the Eyring equation and are found to be 36.833 kJ mol?1 and ?141.518 J K?1 mol?1, respectively.
THE TETRAHYDROPYRANYL ETHER OF (E)-3-BROMO-3-TRIMETHYLSILYL-2-PROPEN-1-OL, A SINGLE SYNTHON FOR THE (E)-β-FORMYLVINYL ANION AND CATION
Miller, R. Bryan,Al-Hassan, Mohamed I.
, p. 2055 - 2058 (1983)
The tetrahydropyranyl ether of (E)-3-bromo-3-trimethylsilyl-2-propen-1-ol can serve as a single synthon for both the (E)-β-formylvinyl anion and cation depending upon the manner in which the bromine group is stereospecifically replaced by an alkyl group.
Method for preparing crotonaldehyde from ethanol
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Paragraph 0019-0048, (2021/06/13)
The invention relates to a method for preparing crotonaldehyde from ethanol. The method comprises the following steps of firstly, dehydrogenating ethanol into acetaldehyde by using a metal-loaded semiconductor photocatalyst under illumination, then carrying out aldol condensation under base catalysis, and finally dehydrating under a heating condition to form crotonaldehyde. The method starts from ethanol and has the advantages of wide raw material sources, mild reaction conditions and the like.
Copper-Containing Catalysts Based on Cerium–Zirconium Oxide Supports in Ethanol Conversion Reaction According to In Situ IR Spectroscopic Data
Ilichev, A. N.,Korchak, V. N.,Matyshak, V. A.,Sil’chenkova, O. N.
, p. 404 - 417 (2021/06/14)
Abstract: Copper-containing catalysts based on CeO2–ZrO2 solid solutions were prepared by the Pecini method and studied using a set of physicochemical methods. It was found that the bond strength of oxygen on the catalyst surface, which depends on the properties of supported copper oxide clusters and a ratio between CeO2 and ZrO2 in the support, plays a main role in ethanol conversion. Ethoxy groups, acetate and formate complexes, and condensation products were detected as main surface intermediates formed in the course of ethanol conversion on the catalysts. The decomposition of the formate complexes was the key stage in the formation of hydrogen. Its appearance on the surface of the catalysts was due to the competition between the reactions of formate and acetate complex formation for oxygen with suitable properties.
