- SBA-15-Functionalized 3-Oxo-ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal-Free Conditions
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The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.
- Karimi, Babak,Farhangi, Elham,Vali, Hojatollah,Vahdati, Saleh
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- Copper-doped sulfonic acid-functionalized MIL-101(Cr) metal–organic framework for efficient aerobic oxidation reactions
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A series of Cr-based metal–organic framework MIL-101-SO3H bearing sulfonic acid functional groups were utilized for the immobilization of catalytically active copper species via a post-synthetic metalation method. The novel materials were fully characterized by scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), the Brunauer–Emmett–Teller method, and thermogravimetric analysis. XPS and the EDX element map both suggested that Cu2+ is coordinately bonded to the MIL-101-SO3H, which forms the MIL-101-SO3@Cu structure. The obtained copper-doped MIL-101-SO3@Cu-1, MIL-101-SO3@Cu-2, and MIL-101-SO3@Cu-3 catalysts were utilized in the selective oxidation of alcohols and epoxidation of olefins using molecular oxygen as an oxidant. Catalytic aerobic oxidation optimization showed that MIL-101-SO3@Cu-1 is the optimal catalyst and it can be reused ten times without compromising the yield and selectivity.
- Li, Xiujuan,Zhou, Zihao,Zhao, Yuzhen,Ramella, Daniele,Luan, Yi
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- Aerobic oxidation of alcohols using various types of immobilized palladium catalyst: The synergistic role of functionalized ligands, morphology of support, and solvent in generating and stabilizing nanoparticles
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Preparation and characterization of a variety of immobilized palladium catalyst, based on either ligand functionalized amorphous or ordered mesoporous silica, is described. The resulting Pd-loaded materials act as efficient catalyst for the oxidation of a variety of alcohols using molecular oxygen and air. Our studies show that in the case of supported palladium catalyst on hybrid amorphous silica, the nature of ligand and the solvent could effectively control the generation of nanoparticles. Furthermore, we have found that nanoparticles with smaller size and higher activity were generated from the anchored palladium precursor when the aerobic oxidation of alcohols was carried out in α,α,α-trifluorotoluene (TFT) instead of toluene. On the other hand, in the case of aerobic oxidation reactions by using supported palladium catalyst on hybrid SBA-15, the combination of organic ligand and ordered mesoporous channels resulted in an interesting synergistic effect that led to enhanced activity, prevention of Pd nanoparticles agglomeration, and finally generation of a durable catalyst.
- Karimi, Babak,Zamani, Asghar,Abedi, Sedigheh,Clark, James H.
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- Studies on the synthesis of elegan-type linear diterpenes: The efficient total syntheses of eleganolone, eleganolone acetate, elegandiol, eleganonal, and epoxyeleganolone
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The first total syntheses of five elegan-type linear diterpenes- eleganolone (1), eleganolone acetate (2), elegandiol (3), eleganonal (4), and epoxyeleganolone (5)-were accomplished starting from (E,E)-farnesol (6) via four to six steps, successively, with high overall yield. The key step was the alkylation reaction of silyl cyanide with allylic iodide.
- Li,Lan,Liu,Li
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- A comparison of intrazeolite and solution singlet oxygen ene reactions of allylic alcohols
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The singlet oxygen ene reactions of four allylic alcohols and for comparison an allylic ether have been examined both in solution and in zeolite Y. Bronsted acid sites in the zeolite were shown to induce decomposition of several of the allylic alcohols. Treatment of the zeolites with pyridine removed these acid sites and allowed intrazeolite reactions of the allylic alcohols without interference from decomposition. Control reactions with an allylic alcohol that is inert to decomposition provided evidence that the presence of pyridine in the zeolite labyrinth does not influence the product composition.
- Clennan, Edward L.,Zhang, Dong,Singleton, Jamie
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- A highly recyclable magnetic core-shell nanoparticle-supported TEMPO catalyst for efficient metal- and halogen-free aerobic oxidation of alcohols in water
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The selective oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is one of the most challenging reactions in organic chemistry. Many oxidizing reagents such as stoichiometric CrVI salts, DMSOcoupled reagents, and hypervalent iodine have been traditionally used to accomplish this transformation. However, these reagents show poor atom efficiency and are often toxic; their widespread use thereby causes significant environmental concerns that render them impractical. As a consequence, due to ever-increasing environmental standards and economic pressures, there is substantial interest towards the use of heterogeneous and recyclable catalysts to achieve the efficient oxidation of alcohols with molecular oxygen or air as the oxidant. Whereas methodologies for the improvement of catalytic activities and selectivities have been developed considerably, they may possibly leave toxic traces of heavy metals in the products. Moreover, many of the metal-based catalyst systems are often deactivated because of the occupation of coordination sites with the by-produced water and so they generally require the use of organic solvents. Therefore, it seems that there is still a great interest in developing efficient and non-metallic catalysts for the aerobic oxidation of alcohols from the viewpoint of socalled green and sustainable chemistry. Of particular interest in this area is the application of the stable nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in combination with various types of non-metallic, stoichiometric co-oxidants as an alternative to metal-based oxidants.
- Karimi, Babak,Farhangi, Elham
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- Intensification of TEMPO-mediated aerobic alcohol oxidations under three-phase flow conditions
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Various homogeneous and heterogeneous catalytic systems based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and different (co-)oxidants have been reported for the selective oxidation of alcohols. Herein we report the use of a commercially available silica-immobilized TEMPO catalyst, in combination with catalytic amounts of HNO3 as a NOx source under continuous three-phase flow conditions. First the stability of the catalyst was evaluated with benzyl alcohol and the reaction parameters were optimized. Subsequently different substrates were tested, focusing on the oxidation of renewable substrates like lactic acid and 5-hydroxymethylfurfural (HMF).
- Aellig, Christof,Scholz, David,Conrad, Sabrina,Hermans, Ive
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- Shape-selective isomerisation of α-acetylenic alcohols to α,β-ethylenic carbonyl compounds by vanadium-pillared montmorillonite catalyst
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A very simple, convenient method for an efficient shape-selective isomerisation of acyclic and aromatic α-acetylenic alcohols only, to the corresponding α,β-ethylenic carbonyl compounds, leaving the cyclic ones unreacted using catalytic amounts of vanadium-pillared montmorillonite catalyst, having -Si-O-V=0 groups with successful reusability is described.
- Choudary,Durga Prasad,Valli
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- Properties of Ti-beta zeolites synthesized by dry-gel conversion and hydrothermal methods
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The large-pore beta zeolite containing Ti has been synthesized in the presence of alkali cations (Na+) by a dry-gel conversion (DGC) technique using tetraethylammonium hydroxide (TEAOH) as a structure-directing agent. The obtained Ti-beta zeolites were compared with hydrothermally synthesized (HTS) Ti-beta. It was found that Ti-beta-DGC samples adsorbed less water (12-13 wt %) than Ti-beta-HTS (19 wt %), indicating that Ti-beta-DGC is more hydrophobic than Ti-beta-HTS. We propose that this leads to a higher activity for the former in the oxidation of cyclohexane. Upon being washed with H2SO4, the turnover number (TON) of DGC samples slightly increased for the oxidation of cyclohexane. DGC and HTS samples demonstrated no significant difference in the activity for oxidation reactions of unsaturated alcohols and C6-C8 cyclic alcohols.
- Tatsumi, Takashi,Jappar, Nizamidin
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- Au/Cu-fiber catalyst with enhanced low-temperature activity and heat transfer for the gas-phase oxidation of alcohols
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A microfibrous-structured gold catalyst was successfully prepared by gold galvanic deposition on a thin-sheet sinter-locked Cu-fibers. The catalyst has excellent heat transfer ability and enhanced low-temperature activity suitable for gas-phase oxidation of alcohols. The AuCu(alloy)-Cu2O active composites formed during reaction and their cooperative effect contribute to promoting the low-temperature activity.
- Zhao, Guofeng,Hu, Huanyun,Deng, Miaomiao,Ling, Min,Lu, Yong
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- Selective organic transformation over a self-assembled all-solid-state Z-scheme core-shell photoredox system
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Z-Scheme artificial photosystems, resembling the natural photosynthesis procedure, circumvent the disadvantage of a single-ingredient photosystem and hold fascinating prospects for solar energy conversion. Despite the advancements, bottom-up elaborate design of composite heterostructured Z-scheme photosystems by flexible interface engineering for photoredox organic transformation has been poorly investigated. We herein report the construction of a metal-based Z-scheme photoredox systemviaa progressive self-assembly strategy integrated with a facile photo-deposition. Tailor-made hierarchically branched ligand-capped Pd nanocrystals (NCs) sandwiched in-between a WO3nanorod (NR) core and CdS shell are harnessed as the charge transport modulator to regulate the interfacial oxidation-reduction kinetics for boosted Z-scheme photocatalysis. The intermediate Pd NCs as Schottky-type electron flow mediators considerably accelerate the unidirectional Z-scheme charge motion rate, endowing multilayered WO3?Pd?CdS core-shell heterostructures with significantly boosted net efficiency of photoactivities toward anaerobic selective nitroaromatic reduction to amino derivatives and aromatic alcohol oxidation to aldehydes under visible light illumination. The predominant active species produced in the versatile photocatalytic selective organic transformation were explored and photocatalytic mechanisms were thus ascertained. Our endeavor could offer a promising route for smartly crafting diverse heterostructured Z-scheme photoredox systems for solar energy conversion.
- Fu, Xiao-Yan,Hou, Shuo,Lin, Xin,Mo, Qiao-Ling,Wei, Zhi-Quan,Xiao, Fang-Xing,Xu, Shuai
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- Supported palladium nanoparticles on hybrid mesoporous silica: Structure/activity-relationship in the aerobic alcohol oxidation using supercritical carbon dioxide
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The preparation, characterization, and catalytic properties of Pd nanoparticles supported on mesoporous organic-inorganic hybrid materials are described for continuous-flow aerobic oxidation of alcohols using supercritical carbon dioxide (scCO2) as a mobile phase. The nanoparticles were generated "bottom-up" from molecular precursors that were precoordinated to the support through suitable anchor units. The most active material allows high single-pass conversions in scCO2 at temperatures as low as 60 °C. This high activity may be associated with the presence of small primary crystallites (approx. 2 nm) that conglomerate to ensembles about 25 nm in size, leading to a larger number of high-indexed planes in small volume units. These findings may provide useful guidelines for further catalyst design on the nanoscale for green oxidation methods.
- Hou, Zhenshan,Theyssen, Nils,Brinkmann, Axel,Klementiev, Konstantin V.,Gruenert, Wolfgang,Buehl, Michael,Schmidt, Wolfgang,Spliethoff, Bernd,Tesche, Bernd,Weidenthaler, Claudia,Leitner, Walter
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- First total synthesis of (±) Hedaol B
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Hedaol B, a new bisnorditerpene isolated from the Japanese brown alga Sargassum. sp., was first synthesized starting from geranyl acetone, alkylation of silyl cyanide as the key step.
- Li, Ying,Lu, Biao,Li, Chunhong,Li, Yulin
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- Functionalized poly(ethylene glycol)-stabilized water-soluble palladium nanoparticles: Property/activity relationship for the aerobic alcohol oxidation in water
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The preparation, characterization, and catalytic properties of water-soluble palladium nanoparticles stabilized by the functionalized- poly(ethylene glycol) as a protective ligand were demonstrated for aerobic oxidation of alcohols in aqueous phase. UV/vis spectra and X-ray photoelectron spectroscopy (XPS) proved that there was an electronic interaction between the bidentate nitrogen ligand and palladium atoms. Transmission electron microscopy and XPS analysis showed that the particle size and surface properties of the generated palladium nanoparticles can be controlled by varying the amount of protective ligand and the kinds of reducing agents. It was found that both the size and surface properties of palladium nanoparticles played very important roles in affecting catalytic performance. The stabilized metallic palladium nanoparticles were proven to be the active centers for benzyl alcohol oxidation in the present system, and the water-soluble Pd nanocatalysts can also be extended to the selective oxidation of various alcohols.
- Feng, Bo,Hou, Zhenshan,Yang, Hanmin,Wang, Xiangrui,Hu, Yu,Li, Huan,Qiao, Yunxiang,Zhao, Xiuge,Huang, Qingfa
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- MagtrieveTM an Efficient, Magnetically Retrievable and Recyclable Oxidant
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MagtrieveTM is a mild and selective oxidant for a variety of alcohols and, in addition to being magnetically retrievable, is superior to activated MnO2 in most cases - particularly for less active alcohols such as simple alkanes. - Key Words: chromium dioxide, manganese dioxide, oxidation, alcohols, aldehydes, ketones.
- Lee, Ross A.,Donald, Dennis S.
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- In situ generation of 2-iodoxybenzoic acid (IBX) in the presence of tetraphenylphosphonium monoperoxysulfate (TPPP) for the conversion of primary alcohols into the corresponding aldehydes
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Primary alcohols are oxidized to the corresponding aldehydes by tetraphenylphosphonium monoperoxysulfate (TPPP) in the presence of catalytic 2-iodobenzoic acid. Overoxidation to carboxylic acids is not observed, in contrast to the use of catalytic 2-iodobenzoic acid with Oxone as reoxidant. Georg Thieme Verlag Stuttgart.
- Bulman Page, Philip C.,Appleby, Louise F.,Buckley, Benjamin R.,Allin, Steven M.,McKenzie, Michael J.
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- Isomerization of allylic alcohols to carbonyl compounds by aqueous-biphase rhodium catalysis
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Isomerization of allylic and homoallylic alcohols is catalyzed by the zwitterionic Rh(I) complex (sulphos)Rh(cod) in water-n-octane to give the corresponding aldehyde or ketone in high yields and chemoselectivity. A π-allyl metal hydride mechanism is proposed on the basis of various independent experiments in both homogeneous and biphasic systems [sulphos = -O3S(C6H4)CH2C(CH2 PPh2)3].
- Bianchini,Meli,Oberhauser
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- Pd-Catalyzed Dehydrogenative Oxidation of Alcohols to Functionalized Molecules
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A dehydrogenative oxidation reaction of primary alcohols to aldehydes catalyzed by a simple Pd/Xantphos catalytic system was developed under an argon or nitrogen atmosphere without oxidizing agents or hydrogen acceptors. The reaction product could be easily changed: under aerobic conditions, esters were obtained in aprotic solvents, whereas the corresponding carboxylic acids were produced in aqueous media. These oxidizing processes were applicable to the efficient synthesis of useful nitrogen-containing heterocyclic compounds such as indole, quinazoline, and benzimidazole via intramolecular versions of this reaction from amino alcohols.
- Mori, Takamichi,Ishii, Chihiro,Kimura, Masanari
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- Aldol condensation reactions of acetone and formaldehyde over vanadium phosphate catalysts: Comments on the acid-base properties
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The self-aldol condensation of acetone and the condensation of acetone with formaldehyde over vanadium phosphate catalysts was studied. Catalysts containing only acid sites, i.e., the V4+ phases (VO)2P2O7 and VOHPO4·0.5H2O were selective for the formation of isophorone from acetone alone and methyl vinyl ketone from the reaction of acetone and formaldehyde. Catalysts containing V5+ phases showed basic and acidic sites and were not selective to these products and only formed hydrocarbons. However, for the Aldol condensation of acetone and the decomposition of 2-methyl-3-butynol (MBOH), the catalyst activity was short lived and deactivation was observed due to coke formation on the catalyst surface. For the reaction of MBOH, the data gave a linear relationship for a Cremer-Constable plot due to the high heat of adsorption of MBOH dominating the energies of the overall catalyzed reaction.
- Hutchings,Kelly,Tanner,David Jackson,Gill,Wells,Bailie
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- Mechanism of Hydrolysis of Allenyl Acetates
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The acid-catalyzed hydrolyses of R2C=C=CHOAc proceed by two mechanisms depending upon the degree of substitution at C-3.The monomethyl derivative exhibits acidity dependence, activation parameters, and solvent isotope effect, kH2O/kD2O = 0.87, characteristic of normal ester hydrolysis, while the dimethyl derivative exhibits behavior characteristic of a slow proton transfer mechanism with kH2O/kD2O = 1.46.A study of α- and β-secondary isotope effects in the hydrolysis of the dimethyl derivative strongly supports this conclusion.For this compound, kH/kα-D = 1.00 and kH/kβ-d6 = 1.08.
- Scheffel, Doris J.,Cole, A. Randolph,Jung, Dorothy M.,Schiavelli, M. D.
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- Pd-Catalyzed Redox Divergent Coupling of Ketones with Terpenols
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Redox diversity is a common and important feature of nature. Herein, a Pd-catalyzed redox divergent coupling of ketones with terpenols has been developed to access α-substituted ketones with varying degrees of unsaturation. The control of oxidation states of the product is facilitated by employing different additives. With the aid of BnOH as an external hydrogen source, a reductive coupling pathway is thermodynamically favored. The use of LiBr as the additive will reduce the reactivity of Pd-H to divert the selectivity toward α,β-unsatuated ketones. By switching the solvent from toluene to chlorobenzene, the active species Pd-H will be fully quenched to enable oxidative coupling. Gram-scale reaction with lower catalyst loading (0.5 mol %) was also accomplished to highlight the practicability of this protocol. Furthermore, detailed experimental studies were carried out to elucidate the reaction mechanism and the factors enabling manipulation of the redox selectivity. This redox divergent coupling protocol provides an important complement for known precedents on Tsuji-Trost allylation of ketones.
- Zhao, Chao-Yang,Ji, Ding-Wei,Zheng, Hao,He, Gu-Cheng,Liu, Heng,Hu, Yan-Cheng,Chen, Qing-An
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- Cis-dioxomolybdenum(VI) complexes as new catalysts for the Meyer-Schuster rearrangement
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We describe a new catalytic system for the isomerisation of propargylic alcohols into α,β-ethylenic carbonyl derivatives (Meyer-Schuster rearrangement), based on the combination of dioxomolybdenum(IV) catalysts and sulfoxides.
- Lorber, Christian Y.,Osborn, John A.
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- Palladium nanoparticles confined in the nanocages of SBA-16: Enhanced recyclability for the aerobic oxidation of alcohols in water
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Via modification of mesoporous cage-like material SBA-16 followed by adsorption of Pd(OAc)2 and reduction with NaBH4, Pd nanoparticles with a uniform size distribution were successfully confined in the nanocages of SBA-16, leading to a new solid catalyst for the aerobic oxidation of alcohols. The solid catalyst was characterized with N2 sorption, XRD, TEM, FT-IR and XPS. Such a catalyst showed a high activity for the oxidation of benzylic alcohols, 1-phenylethanol and allylic alcohols without the presence of bases under air or O2 atmosphere in water even at room temperature. The selectivities for the corresponding aldehydes and ketones were more than 99% in all the cases investigated. The developed catalyst could be facilely recovered and reused twelve times without significant decreases in activity and selectivity. Its recyclability was much better than that of the catalyst derived from amorphous silica under the same conditions.
- Ma, Zhancheng,Yang, Hengquan,Qin, Yong,Hao, Yajuan,Li, Guang
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- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
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In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
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- Rhodium(I)-Catalyzed Intermolecular Aza-[4+3] Cycloaddition of Vinyl Aziridines and Dienes: Atom-Economical Synthesis of Enantiomerically Enriched Functionalized Azepines
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A new synthetic application of vinyl aziridines as N-containing three-atom components in a rhodium-catalyzed [4+3] cycloaddition reaction is described. The reaction proceeds well with various silyl dienol ethers and vinyl aziridines, and enables the efficient synthesis of highly functionalized azepines in an enantioselective manner with net inversion of absolute configuration. The salient features of the transformation include the use of readily available substrates, high selectivity, and mild reaction conditions, as well as the versatile functionalization of the products.
- Zhu, Chao-Ze,Feng, Jian-Jun,Zhang, Junliang
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- Yolk-shell hybrid materials with a periodic mesoporous organosilica shell: Ideal nanoreactors for selective alcohol oxidation
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This contribution describes the preparation of multifunctional yolk-shell nanoparticles (YSNs) consisting of a core of silica spheres and an outer shell based on periodic mesoporous organosilica (PMO) with perpendicularly aligned mesoporous channels. The new yolk-shell hybrid materials were synthesised through a dual mesophase and vesicle soft templating method. The mesostructure of the shell, the dimension of the hollow space (4～52 nm), and the shell thickness (16～34 nm) could be adjusted by precise tuning of the synthesis parameters, as evidenced by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption investigations. Various metal nanoparticles (e.g., Au, Pt, and Pd) were encapsulated and confined in the void space between the core and the shell using impregnation and reduction of adequate metal precursors. The selective oxidation of various alcohol substrates was then carried out to illustrate the benefits of such an architecture in catalysis. High conversion (～100%) and excellent selectivity (～99%) were obtained over Pd nanoparticles encapsulated in the hybrid PMO yolk-shell structures.
- Liu, Jian,Yang, Heng Quan,Kleitz, Freddy,Chen, Zhi Gang,Yang, Tianyu,Strounina, Ekaterina,Lu, Gao Qing,Qiao, Shi Zhang
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- Gas-liquid segmented flow microfluidics for screening copper/tempo-catalyzed aerobic oxidation of primary alcohols
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Aerobic oxidation using a combination of copper salts and 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO) represent useful tools for organic synthesis and several closely related catalyst systems have been reported. To gain further insights, these catalytic systems were evaluated in a gas-liquid segmented flow device. The improvement of oxygen mass transfer has a significant influence on the turnover-limiting step. Hence, an improved catalytic system using copper(II) as copper source was implemented in a microreactor for the safe and efficient oxidation of primary alcohol.
- Vanoye, Laurent,Pablos, Mertxe,De Bellefon, Claude,Favre-Réguillon, Alain
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- Building MOF bottles (MIL-101 family as heterogeneous single-site catalysts) around Fe3O4 ships: A highly efficient and magnetically separable catalyst for oxidation of alcohols
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Fe3O4 supported on chromium-based metal-organic framework (MOF), MIL-101(Cr), has emerged as highly efficient and heterogeneous catalyst for selective oxidation of alcohols because of its high specific surface area, tuneable pore size, and unique structure. MIL-101 and its Fe3O4 composite (Fe3O4@MIL-101) was prepared via the impregnation of the Fe3O4 in MIL-101. The surface properties of the functionalized catalyst were analyzed by a series of characterization techniques like FTIR, XRD, N2 adsorption-desorption, and TEM. XRD and adsorption-desorption analysis show that the mesostructure of MIL-101 remains intact after Fe3O4 modifications, while spectral technique show the successful immobilizing of the neat Fe3O4 inside the MIL-101 support. Fe3O4@MIL-101 can be reused several times although they get less active.
- Naghdi, Zahra,Farzaeli, Razieh,Aliyan, Hamid
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- Model Studies of Terpene Biosynthesis. Intermolecular 1'-2 Electrophilic Condensation of 3-Methyl-2-butenyl Acetate
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The stereochemistry of the carbon-carbon bond-forming step in the electrophilic intermolecular 1'-2 condensation of 3-methyl-2-butenyl acetate (1-OAc) to yield lavandulyl acetate (2-OAc) was studied.Treatment of (1S)-3-methyl-2-butenyl acetate ((1S)-1-OAc) with aluminum trichloride in ethyl acetate gave labeled lavandulyl acetate (2-OAc) (30percent) and isoprene (65percent) as the major products.The configurations at C(1), C(2), and C(3) and the relative abundances of the diastereomers of 1-OAc were determined by converting the mixture to 3-(2'-propyl)-butyrolactone (3).The intensities of 1H resonances characteristic of each diastereomer were measured with the aid of Pirkle's chiral shift reagent, (S)-(+)-2,2,2-trifluoro-1-(9-anthryl)ethanol.The analysis showed that equal amounts of the (1S,2S,3R), (1S,2R,3R), (1S,2S,3S), and (1S,2R,3S) diastereomers of 2-OAc were obtained, signifying that the 1'-2 condensation was stereorandom at C(1) of the electrophilic isoprene unit.
- King, Chi-Hsin R.,Poulter, C. Dale
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- Sustainable catalytic oxidation of alcohols over the interface between air and water
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Alcohols are oxidized to aldehydes or ketones in water by directly using air as the oxidant. The catalytic conversions are based on a hybrid nanocatalyst with monodispersed Au nanoparticles embedded in a polyoxometalate self-assembly matrix. The oxidation processes exhibit excellent activity and selectivity.
- Huang, Zhijun,Li, Fengbo,Chen, Bingfeng,Yuan, Guoqing
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- Controlling the selectivity of the manganese/bicarbonate/hydrogen peroxide catalytic system by a biphasic pyrrolidinium ionic liquid/n-heptane medium
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The Mn2+/HCO3-/H2O2 catalytic system exhibits excellent aldehyde selectivity in the oxidation of various benzylic and allyic alcohols under mild conditions and short reaction time when the reactions are carried out in a biphasic dicationic pyrrolidinium ionic liquid/n-heptane medium. The dicationic pyrrolidinium ionic liquid shows differential solubility towards alcohols and their aldehydes whereas the immiscible n-heptane instantaneously extracted and separated aldehydes from the reaction phase. This design of biphasic ionic liquid/n-heptane catalytic system prevents the over-oxidation of aldehydes to carboxylic acids effectively. Separation and recycling can also be easily done by decantation of the n-heptane layer after reaction. With the biphasic system, high conversion of benzyl alcohol to benzaldehyde was achieved with very low loadings of H 2O2 and Mn(OAc)2 catalyst at room temperature and within short reaction time. Throughout 10 reaction cycles, a total turnover number (TON) of 37,600 was achieved and excellent catalytic reactivity and selectivity were maintained with an average yield of 94%.
- Wong, Wing-Leung,Ho, Kam-Piu,Lee, Lawrence Yoon Suk,So, Ming-Him,Chan, Tak Hang,Wong, Kwok-Yin
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- Structure, texture, acidity and catalytic performance of AlPO4-caesium oxide catalysts in 2-methyl-3-butyn-2-ol conversion
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A series of aluminium orthophosphate-caesium oxide systems with various caesium oxide loadings (5-30 wt%) were prepared by impregnation of ALPO4 with a methanolic solution of caesium acetate and characterized by TG/DTA, XRD, DRIFT, Raman, SEM-EDX, XPS, 27Al and 31P MAS NMR and nitrogen adsorption. Aluminium orthophosphate remained amorphous with caesium oxide incorporation when calcined at 873 K for 3 h. After thermal treatment at 1423 K it crystallized in the tridymite form except for materials containing 30 wt% caesium oxide. DRIFT spectroscopy showed that the P-OH stretching vibration at 3670 cm-1 decreased in intensity with caesium oxide loading. Materials at 20-30 wt% caesium oxide did not exhibit any hydroxyl bands. Besides, Al and P atoms remained in tetrahedral coordination as in unmodified aluminium orthophosphate. Moreover, the incorporation of caesium oxide leads, simultaneously, to a progressive decrease in surface area and pore volume (larger at 30 wt% caesium oxide) as well as to an increase in the most frequently occurring pore radius. On the other hand, caesium oxide reduced both the number and strength of acid sites as the caesium content increased. Consequently, 2-methylbut-3-yn-2-ol (MBOH) underwent almost exclusively dehydration to 3-methyl-3-buten-1-yne (acid activity) on pure AlPO4, whereas its modification with increasing amounts of caesium oxide developed AlPO4- based materials with increased basic properties and hence high selectivities (99 mol%) to the base-catalysed cleavage of MBOH yielding acetone and acetylene.
- Bautista, Felipa M.,Campelo, Juan M.,Garcia, Angel,Leon, Raquel M.,Luna, Diego,Marinas, Jose M.,Romero, Antonio A.,Navio, Jose A.,Macias, Manuel
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- A recoverable sandwich phosphorotungstate stabilized palladium (0) catalyst for aerobic oxidation of alcohols in water
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The preparation, characterization and catalytic properties of tetra metal substituted sandwich phosphorotungstate [M4(H2O)2(PW9O34)2]10?(M4P2W18, M2+?=?Fe2+, Co2+, Mn2+, Cu2+, VO2+) stabilized Pd nanoparticles, which were in-situ encapsulated in mesoporous aluminum phosphate (mAPO) by a one-pot method, were demonstrated for aerobic oxidation of alcohol in water. The synthesized catalysts were characterized with N2 adsorption, XRD, TEM, FT-IR and UV–vis. TEM analysis revealed that Pd-M4P2W18/mAPO thus obtained has a mean palladium particle size of less than 5?nm. The solid Pd-M4P2W18/mAPO catalysts exhibit excellent activity for aerobic oxidation of benzyl alcohols in water without any base additives. It was found the introduced M4P2W18 polyoxanions encapsulated palladium nanoparticles as both stabilizing agent and promoters, leading to enhanced activity and recyclability of palladium catalyst. The recycling test of representative Pd-(VO)4P2W18/mAPO for oxidation of benzyl alcohol suggested no significant decrease in activity and selectivity even after twelve times of successive reactions. This novel heterogeneous catalyst composed of polyoxometalates stabilized palladium nanocatalysts and mesoporous aluminophosphate can also be extended to the selective oxidation of various alcohols.
- Chen, Lijuan,Feng, Tao,Wang, Pengfei,Chen, Ziwen,Yan, Riqing,Liao, Bo,Xiang, Yujun
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- Oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds with aqueous hydrogen peroxide under organic solvent-free conditions
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Allylic alcohols are chemoselectively oxidized to α,β- unsaturated carbonyl compounds in high yield with aqueous H2O 2 in the presence of Pt black catalyst under organic solvent-free conditions. The catalyst is easily recyclable and effective for at least 7 cycles. The Royal Society of Chemistry.
- Kon, Yoshihiro,Usui, Yoko,Sato, Kazuhiko
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- Cetonisation catalytique du methyl-2-butene-3-ol par des complexes du rhodium(III) ou du palladium(II)
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A number of efficient catalytic procedures for the oxidation of acid-sensitive substrate such as 2-methyl-3-buten-2-ol to the corresponding ketone (2-methyl-butan-2-ol-3-one) are compared.Reaction with dioxygen (or quinone) and a palladium precursor (PdCl2 or ) under mild conditions (=35 deg C), gave good conversions (98percent) and good selectivities (=90percent).
- Derdar, Fatma,Martin, Jacques,Martin, Claudine,Bregeault, Jean-Marie,Mercier, Jacqueline
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- In situ synthesis of hierarchical In2S3-graphene nanocomposite photocatalyst for selective oxidation
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We report a simple, in situ hydrothermal way to fabricate In2S3-graphene (GR) nanocomposites in which hierarchical In2S3 "petals" spread over the surface of GR sheets in virtue of the "structure directing" role of graphene oxide (GO) as the precursor of GR in a solution phase. With the addition of an appropriate amount of GO, the hierarchical petal-like In2S3 structures have been successfully grown on the two-dimensional (2D) GR "mat". The as-synthesized In2S3-GR nanocomposites featuring good interfacial contact exhibit much higher photocatalytic activity toward selective oxidation of alcohols under visible light irradiation than blank In2S3. A series of characterization results disclose that the significantly enhanced photocatalytic performance of In2S3-GR nanocomposites can be ascribed to the integrative effect of the increased separation and transfer efficiency of photogenerated electron-hole pairs and the larger surface area. This work highlights the wide scope of fabricating GR-based semiconductor nanocomposites with specific architectural morphology by rationally utilizing the "structure directing" property of GO and extending their applications toward photocatalytic selective transformations. This journal is
- Li, Xiuzhen,Weng, Bo,Zhang, Nan,Xu, Yi-Jun
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- The Remarkable Amphoteric Nature of Defective UiO-66 in Catalytic Reactions
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One of the major requirements in solid acid and base catalyzed reactions is that the reactants, intermediates or activated complexes cooperate with several functions of catalyst support. In this work the remarkable bifunctional behavior of the defective UiO-66(Zr) metal organic framework is shown for acid-base pair catalysis. The active site relies on the presence of coordinatively unsaturated zirconium sites, which may be tuned by removing framework linkers and by removal of water from the inorganic bricks using a dehydration treatment. To elucidate the amphoteric nature of defective UiO-66, the Oppenauer oxidation of primary alcohols has been theoretically investigated using density functional theory (DFT) and the periodic approach. The presence of acid and basic centers within molecular distances is shown to be crucial for determining the catalytic activity of the material. Hydrated and dehydrated bricks have a distinct influence on the acidity and basicity of the active sites. In any case both functions need to cooperate in a concerted way to enable the chemical transformation. Experimental results on UiO-66 materials of different defectivity support the theoretical observations made in this work.
- Hajek, Julianna,Bueken, Bart,Waroquier, Michel,De Vos, Dirk,Van Speybroeck, Veronique
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- Metal oxide coated ceramic corrugated plate catalyst, preparation and application in preparation of key intermediates of citral
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The present disclosure belongs to the technical field of catalysis, and particularly relates to a metal oxide coated ceramic corrugated plate catalyst, its preparation method and application thereof in preparation of key intermediates of citral. The catalyst consists of a ceramic corrugated plate carrier and a metal oxide active layer coated on a surface of the carrier, wherein the metal oxide active layer is a metal oxide formed by active ingredient titanium and at least four other metal elements selected from vanadium, chromium, manganese, iron, zirconium, niobium and molybdenum.
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Page/Page column 8-10
(2021/04/14)
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- Triple-phase Boundary in Anion-Exchange Membrane Reactor Enables Selective Electrosynthesis of Aldehyde from Primary Alcohol
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Oxidation of primary alcohol to the corresponding aldehyde remains a significant challenge, even with the state-of-the-art chemistry. Here, a novel electrochemical system was developed for the exclusive production of aldehyde from primary alcohol using an anion-exchange membrane (AEM) reactor. Oxidation proceeded on a gold catalyst under basic conditions, which largely enhanced the reaction rate. Despite the basic nature around the reaction sites, the oxidation of primary alcohols exclusively yielded the corresponding aldehyde, which was attributed to the unique three-phase interfacial reaction sites in the AEM reactor. In addition to benzyl alcohol, the oxidation of allylic and aliphatic alcohols was also demonstrated. Comparison of constant potential electrolysis with the AEM reactor or a conventional batch-type cell revealed the crucial role of the triple-phase boundary for the selectivity of the oxidation of alcohol.
- Atobe, Mahito,Fukazawa, Atsushi,Furutani, Yuka,Ido, Yuto,Sato, Yasushi,Shida, Naoki
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- Method for synthesizing isovaleraldehyde
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The invention provides a synthetic method of 3-methylcrotonaldehyde. The method comprises the following steps that epoxy isobutane is subjected to a hydroformylation reaction, hydroxy isovaleraldehydeis obtained, hydroxy isovaleraldehyde is subjected to an intramolecular dehydration reaction, and 3-methylcrotonaldehyde is obtained. The synthetic method of 3-methylcrotonaldehyde does not need harsh reaction conditions.
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Paragraph 0033; 0037; 0038; 0042-0043; 0048
(2020/12/05)
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- Modulating charge migration in photoredox organic transformationviaexquisite interface engineering
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Modulating photo-induced charge separation/transfer constitutes a central challenge in heterogeneous photocatalysis. Despite advancements in this area, finely tuning directional electron migration without involving conventional co-catalysts [e.g., metal nanocrystals and transition metal dichalcogenides (TMDs)] for boosted photoredox catalysis has not yet been explored. Herein, we report the exquisite design of a novel and general macromolecule-modulated photoredox selective organic transformation system, wherein an ultrathin macromolecular poly(diallyldimethylammonium chloride) (PDDA) layer was integrated at the interface of wide-band-gap (WBG) and narrow-band-gap (NBG) semiconductors to construct heterostructured photocatalysts. The ultra-thin PDDA interim layer expedites interfacial unidirectional electron transfer from the NBG to WBG semiconductor, resulting in a cascade electron transfer channel. The favorable energy level alignment among the building blocks, intimate interfacial integration and multilayered nanoarchitecture endow the WBG@PDDA@NBG heterostructures with substantially enhanced and versatile photoredox performance toward the selective oxidation of aromatic alcohols to aldehydes and the anaerobic reduction of nitroaromatics to amino compounds under visible light irradiation. This can be ascribed to the crucial role of the ultrathin intermediate PDDA layer as a highly efficient metal and TMD-free charge transfer mediator, relaying the electrons from the NBG to WBG semiconductor and slowing charge recombination. Our work could open up new frontiers to exploit diverse metal and TMD-free photocatalytic systems and provide a first insight into the fine tuning of charge transport utilizing non-conductive ionic polymers for solar energy conversion.
- Xu, Shuai,Huang, Ming-Hui,Li, Tao,Wei, Zhi-Quan,Lin, Xin,Dai, Xiao-Cheng,Hou, Shuo,Fu, Xiao-Yan,Xiao, Fang-Xing
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supporting information
p. 8360 - 8375
(2020/05/16)
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- PROCESS FOR THE PREPARATION OF ALPHA, BETA UNSATURATED ALDEHYDES BY OXIDATION OF ALCOHOLS IN THE PRESENCE OF A LIQUID PHASE
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Process for the preparation of alpha, beta unsaturated aldehydes by oxidation of alcohols in the presence of a liquid phase wherein the liquid phase contains 0.1 to less than 25 weight-% water and wherein the liquid phase contains at least 25 weight-% of alcohol(s) of general formula (II) and alpha, beta unsaturated aldehyde(s) of general formula (I) and wherein the oxidant isoxygen and/or hydrogen peroxide and wherein the catalyst comprises at least one intermetallic compound.
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Paragraph 52
(2020/03/29)
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- PROCESS FOR PRODUCING PRENOL AND PRENAL FROM ISOPRENOL
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The present invention relates to a process for preparing 3-methyl-2-butenol (prenol) and 3-methyl-2-butenal (prenal) from 3-methyl-3-butenol (isoprenol), in which 3-methyl-3-butenol is subjected to a catalytic isomerization over a carbon-supported Pd catalyst in the presence of a gas mixture comprising 1% to 15% by volume of oxygen to obtain a first product mixture, and the first product mixture is subjected to an oxidative dehydrogenation over a Pd catalyst comprising SiO2 and/or Al2O3 as support material, or over a carbon-supported Pd/Au catalyst in the presence of a gas mixture comprising 5% to 25% by volume of oxygen.
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- Preparation method of 3-methyl-2-butena
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The invention provides a preparation method of 3-methyl-2-butena. The preparation method comprises following steps: in the presence of a resin, a catalyst, a solvent, and an acidic gas, methylbutynolis subjected to Meyer-Schuster rearrangement reaction to obtain 3-methyl-2-butena, 3-methyl-2-butena and the solvent are subjected to aldolization so as to obtain an aldolization intermediate; the aldolization intermediate is subjected to deprotection reaction in the resin so to obtain aldolization. The product is high in purity; reaction conditions are mild; the preparation process is green, andno pollution is caused; and industrialized production can be realized.
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Page/Page column 5-7
(2019/10/23)
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- A isopentene aldehyde synthesis process (by machine translation)
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The present invention provides a process for synthesizing isopentene aldehyde, the metal oxide as the catalyst, in the presence of chemicals, in order to 2 - methyl - 3 - [...] - 2 - ol as a raw material for preparing catalytic rearrangement isopentene aldehyde, the invention high catalytic efficiency, good selectivity, yield up to 93.9 - 96.1%, is suitable for industrial production; catalyst used in the invention the price is cheap, consumption, the production cost is reduced; the catalytic system is simple and, follow-up separation step can be simplified, and reducing energy costs; the invention conversion speed, the reaction time is only 20 - 40 min; the catalyst of the invention has good stability, to use the multi-batch still maintaining a relatively high performance, to use the 20 times, reducing the yield of 0.94%. (by machine translation)
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Paragraph 0020-0035
(2019/02/26)
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- General self-assembly of metal/metal chalcogenide heterostructures initiated by a surface linker: Modulating tunable charge flow toward versatile photoredox catalysis
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Interfacial charge separation and transfer enduringly constitutes a core issue, which dictates the efficiency of a photocatalytic reaction. However, the exquisite modulation of directional charge transfer to ideal reaction sites remains challenging in terms of the fast recombination rates of photoinduced charge carriers and the difficulty in constructing spatially separated high-speed charge transfer channels. Herein, we demonstrate the general construction of metal/metal chalcogenide heterostructures by a facile, green, universal, scalable and simple yet efficient electrostatic self-assembly strategy, wherein tailor-made positively charged 4-dimethylaminopyridine (DMAP)-capped metal nanocrystals (NCs, Au, Pd) were spontaneously and intimately tethered on negatively charged one-dimensional (1D) transition metal chalcogenides (TMC: CdS, CdIn2S4, ZnIn2S4, and Zn0.5Cd0.5S) initiated by a surface linker (DMAP) to fabricate well-defined heterostructured photocatalysts. Moreover, the interface configurations between the metal NCs and TMC matrices were finely designed by ligand engineering to afford controllable charge transfer pathways. Intriguingly, this tunable charge flow endows the metal NC/TMC heterostructures with markedly enhanced and versatile photoredox performance toward the anaerobic-selective photoreduction of aromatic nitro compounds, photocatalytic hydrogen generation, and photocatalytic selective oxidation of aromatic alcohols under visible light irradiation, in which metal NCs play imperative roles in efficiently capturing Schottky-junction-driven electrons from the TMC substrates without the interference of the hierarchically branched ligand capped on the metal NCs. Our studysheds light on the rational modulation of interfacial charge flow in photoredox catalysis for substantial solar energy conversion.
- Li, Tao,Huang, Ming-Hui,Li, Yu-Bing,Dai, Xiao-Cheng,He, Yunhui,Xiao, Guangcan,Xiao, Fang-Xing
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p. 21182 - 21194
(2019/10/01)
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- PROCESS FOR THE PREPARATION OF 3-METHYL-2-BUTEN-1-AL
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Process for the preparation of 3-methyl-2-buten-1-al, wherein2-methyl-3-buten-2-ol is reacted to 3-methyl-2-buten-1-al in the presence of a catalyst, wherein the catalyst comprises a catalytically active metal and wherein the reaction is conducted at a pH of ≤ 7.
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Page/Page column 40
(2019/07/13)
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- Nitroxyl radical based conjugated microporous polymers as heterogeneous catalysts for selective aerobic alcohol oxidation
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Covalent anchoring of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) on the scaffold of conjugated microporous polymers (CMPs) was achieved via cost-effective FeCl3-catalyzed oxidative polymerization of dicarbazole functionalized TEMPO. These TEMPO-CMPs exhibit excellent catalytic performance for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the TEMPO-CMPs could be recycled at least 20 times with good retention of high catalytic activities.
- Liu, Mingxuan,Zhou, Baolong,Zhou, Lei,Xie, Zhen,Li, Shen,Chen, Long
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supporting information
p. 9860 - 9865
(2018/06/06)
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- PROCESS FOR THE PREPARATION OF ALPHA, BETA UNSATURATED ALDEHYDES BY OXIDATION OF ALCOHOLS IN THE PRESENCE OF A LIQUID PHASE
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Process for the preparation of alpha, beta unsaturated aldehydes by oxidation of alcohols in the presence of a liquid phase wherein the liquid phase contains 0.1 to less than 25weight-% water and wherein the liquid phase contains at least 25 weight-% of alcohol(s) of general formula (II) and alpha, beta unsaturated aldehyde(s) of general formula (I) and wherein the oxidant is oxygen and/or hydrogen peroxide.
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Page/Page column 46; 47
(2018/10/19)
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- Bicatalytic Multistep Reactions En Route to the One-Pot Total Synthesis of Complex Molecules: Easy Access to Chromene and 1,2-Dihydroquinoline Derivatives from Simple Substrates
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By combining nanocatalysis with base catalysis, a novel one-pot multistep process was found for the synthesis of substituted heterocycles of biological relevance from simple substrates. The process is based on the initial Au/O2 oxidation of allylic alcohols, which is followed by base-catalyzed tandem hetero-Michael/aldolization/crotonization with ortho-hydroxy- or ortho-aminobenzaldehydes. The flexibility of the reaction even allowed the benzaldehyde partner to be prepared in situ in an example of a one-pot/five-step process.
- Giorgi, Pascal D.,Miedziak, Peter J.,Edwards, Jennifer K.,Hutchings, Graham J.,Antoniotti, Sylvain
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- Selective Oxidation of Activated Alcohols by Supported Gold Nanoparticles under an Atmospheric Pressure of O2: Batch and Continuous-Flow Studies
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In the hunt for a simple, mild, and scalable protocol for gold nanoparticle-catalyzed oxidation of benzylic and allylic alcohols under O2, we have used commercially available gold nanoparticles supported on alumina to selectively oxidize a large range of activated alcohols to the corresponding carbonyl compounds in good yields (68–99 %) and with excellent selectivity (ca. 100 %). The true heterogeneous nature of the catalysis by gold was demonstrated, allowing us to further adapt this protocol to continuous-flow reactors by using the tube-in-tube technology, in which higher yields were obtained thanks to an improved oxygenation of the reaction medium.
- Giorgi, Pascal D.,Elizarov, Nelli,Antoniotti, Sylvain
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p. 1830 - 1836
(2017/05/29)
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- Superparamagnetic Core–Shell Metal–Organic Framework Fe3O4/Cu3(btc)2 Microspheres and Their Catalytic Activity in the Aerobic Oxidation of Alcohols and Olefins
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Core–shell structured Fe3O4/Cu3(btc)2 (btc = 1,3,5-benzenetricarboxylate) microspheres have been successfully synthesized by coating the metal–organic frameworks on poly(acrylic acid) (PAA) functionalized Fe3O4 microspheres by the layer-by-layer assembly method. The MOF composite exhibited excellent catalytic activity in the aerobic oxidation of alcohols and the epoxidation of olefins due to the porosity of MOFs and large amount of readily accessible Cu2+. Furthermore, the catalyst could be easily segregated from the catalytic system by using an external magnetic field due to its magnetic properties. The heterogeneous catalyst displayed good reusability and broad reagent scope in the aerobic oxidation of alcohols and epoxidation of olefins.
- Li, Jie,Gao, Hongyi,Tan, Li,Luan, Yi,Yang, Mu
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p. 4906 - 4912
(2016/10/26)
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- Aldol Condensations Catalyzed by Basic Anion-Exchange Resins
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The aldol condensations of various aldehydes with ketones in the presence of anionic (basic) ion-exchange resins have been investigated. Both batch and continuous modes were studied and compared for the reaction of citral (a mixture of geranial and neral) with acetone to give ψ-ionone. Different reaction conditions were investigated, and the performances of five different ion-exchange resins were compared. The most stable resins could be used for 10 cycles in batch mode or 1000 min in continuous mode without a significant loss in activity or selectivity.
- Bonrath, Werner,Pressel, Yann,Schütz, Jan,Ferfecki, Erich,Topp, Klaus-Dieter
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p. 3584 - 3591
(2016/12/14)
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- METHOD FOR PRODUCING α,β-UNSATURATED CARBONYL COMPOUNDS
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PROBLEM TO BE SOLVED: To provide a simple and efficient, novel method for producing α,β-unsaturated carbonyl compounds, which can provide α,β-unsaturated carbonyl compounds from allyl alcohols with high yields under a mild reaction condition, and has extremely little influence and toxicity on the environment and the human body. SOLUTION: Provided is a method for producing α,β-unsaturated carbonyl compounds, the method comprising reacting allyl alcohols and hydrogen peroxide to carbonylate alcohol portions to produce corresponding α,β-unsaturated carbonyl compounds. As a reaction catalyst, there are used an Fe(II) or Fe(III) salt soluble in water or an organic solvent, and at least one picolinic acid selected from 2-picolinic acid and 6-C1-4 alkyl-2-picolinic acid in coexistence in a ratio of 1:1 to 1:4. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0037; 0042-0043
(2016/12/26)
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- Highly efficient sulfonated-polystyrene-Cu(II)@Cu3(BTC)2 core-shell microsphere catalysts for base-free aerobic oxidation of alcohols
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A novel catalyst consisting of a functional sulfonated-polystyrene (SPS) core, a porous Cu3(BTC)2 shell and an active Cu(ii) interface between the core and shell was developed via a facile step-by-step assembly method. The polystyrene core was sulfonated first to achieve functional -SO3H groups on its surface. The main function of the -SO3H groups was to graft Cu(ii) ions to generate an active Cu(ii) interface, and the excess -SO3H could provide acid conditions for the catalytic reaction. The Cu(ii) interface along with the acid conditions and the co-catalyst 2,2,6,6-tetramethyl-piperidyl-1-oxy (TEMPO) enhanced the catalytic activity for the aerobic oxidation of alcohols to aldehydes by molecular oxygen under base-free conditions. A portion of Cu(ii) ions on the SPS surface was then coordinated with H3BTC (1,3,5-benzenetricarboxylic acid) to form a porous Cu3(BTC)2 shell, which could protect the active metal from leaching as well as provide porous channels for mass transfer, resulting in high stability and recyclability in the catalysis procedure. The SPS-Cu(ii)@Cu3(BTC)2 catalyst could be recycled ten times without a significant loss in its activity and selectivity. Furthermore, the SPS-Cu(ii)@CuBDC (BDC = 1,4-benzenedicarboxylate) composite was also synthesized and showed high efficiency for catalyzing the aerobic oxidation of alcohols and aerobic homocoupling of arylboronic acids, suggesting that the unique nanostructure of SPS-Cu(ii)@MOFs can be easily extended to design complex catalysts with high efficiency and good stability for different catalytic reactions. This journal is
- Zhang, Xiaowei,Dong, Wenjun,Luan, Yi,Yang, Mu,Tan, Li,Guo, Yangguang,Gao, Hongyi,Tang, Yinhai,Dang, Rui,Li, Jie,Wang, Ge
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p. 4266 - 4273
(2015/03/04)
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- Imparting magnetic functionality to iron-based MIL-101 via facile Fe3O4 nanoparticle encapsulation: an efficient and recoverable catalyst for aerobic oxidation
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The development of sustainable, easily synthesizable and highly efficient catalysts is a fundamental goal of catalysis science. In this work, highly superparamagnetic nanoparticles (Fe3O4 NPs) were prepared through a modified co-precipitation method and embedded into a Fe-MIL-101 metal-organic-framework through a facile encapsulation strategy. The catalytic activity of Fe3O4/Fe-MIL-101 was investigated in the aerobic oxidation of alcohols and epoxidation of olefines. High yields (up to quantitative conversion) were observed for both reactions under mild conditions. Furthermore, the magnetic NP/MOF catalysts could be easily recovered and recycled; even after usage in eight consecutive reaction batches, no significant loss of catalytic efficiency was observed. This class of catalysts is promising for green and practical large-scale industrial applications.
- Jin, Zhaokui,Luan, Yi,Yang, Mu,Tang, Jia,Wang, Jingjing,Gao, Hongyi,Lu, Yunfeng,Wang, Ge
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p. 78962 - 78970
(2015/10/05)
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- Amphiphilic hollow porous shell encapsulated Au@Pd bimetal nanoparticles for aerobic oxidation of alcohols in water
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This work describes the design, synthesis and analysis of an amphiphilic hollow mesoporous shell encapsulating catalytically active Au@Pd bimetal nanoparticles. The particles exhibited excellent catalytic activity and stability in the aerobic oxidation of primary and secondary alcohols to their corresponding aldehydes or ketones in water when using air as an oxidizing agent under atmospheric pressure.
- Zou, Houbing,Wang, Runwei,Dai, Jinyu,Wang, Yu,Wang, Xue,Zhang, Zongtao,Qiu, Shilun
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supporting information
p. 14601 - 14604
(2015/09/28)
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- Promoting Visible-Light Photocatalysis with Palladium Species as Cocatalyst
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Conventionally, Pd catalysis has been widely used in either heterogeneous or homogeneous thermocatalytic organic synthesis. Herein, we demonstrate a case study on the important, cocatalyst role of Pd nanoparticles in ternary In2S3-(reduced graphene oxide-palladium) [In2S3-(RGO-Pd)] composites for the selective oxidation of alcohols under visible-light irradiation. Pd acts as dual cocatalyst along with RGO to promote the more efficient separation of photogenerated electron-hole pairs and facilitate their spatial transfer across the interface in ternary In2S3-(RGO-Pd) composites, which leads to higher activity than that of binary In2S3-RGO composites. This work highlights the promising scope of using Pd nanoparticles as a cocatalyst for promoting visible-light photocatalysis towards selective organic transformations under ambient conditions.
- Li, Xiuzhen,Zhang, Nan,Xu, Yi-Jun
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p. 2047 - 2054
(2015/03/14)
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- Hydrogenation of allyl alcohols catalyzed by aqueous palladium and platinum nanoparticles
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A series of Pd and Pt nanoparticles (NPs) was prepared starting from the corresponding metal ions and lignosulphonates; NPs were tested as catalysts for allyl alcohols hydrogenation in water at room temperature and pressure. All NPs were active with sharp differences in conversions and selectivities: Pt NPs formed mainly saturated alcohols, whereas Pd NPS were more active, but less selective, forming, in addition to saturated alcohols, also isomeric unsaturated alcohols and aldehydes, both saturated and unsaturated.
- Di Pietrantonio, Krystel,Coccia, Francesca,Tonucci, Lucia,D'Alessandro, Nicola,Bressan, Mario
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p. 68493 - 68499
(2015/09/01)
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- Water-Soluble Gold-N-Heterocyclic Carbene Complexes for the Catalytic Homogeneous Acid- and Silver-Free Hydration of Hydrophilic Alkynes
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Water-soluble gold(III/I) N-heterocylic carbene complexes behave as efficient catalysts for the hydration of terminal alkynes in neat water. The transformation proceeds in the absence of Bronsted acids or halide scavengers and is suitable for sensitive substrates. Kinetic profiles and DFT studies provide a clear picture of intermediates present during catalysis.
- Ibrahim, Houssein,Defrmont, Pierre,Braunstein, Pierre,Thry, Vincent,Nauton, Lionel,Cisnetti, Federico,Gautier, Arnaud
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p. 3893 - 3900
(2016/01/25)
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- Selective oxidation of allylic alcohols over highly ordered Pd/meso-Al 2O3 catalysts
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Highly ordered mesoporous alumina was prepared via evaporation induced self assembly and was impregnated to afford a family of Pd/meso-Al2O 3 catalysts for the aerobic selective oxidation (selox) of allylic alcohols under mild reaction conditions. CO chemisorption and XPS identify the presence of highly dispersed (0.9-2 nm) nanoparticles comprising heavily oxidised PdO surfaces, evidencing a strong palladium-alumina interaction. Surface PdO is confirmed as the catalytically active phase responsible for allylic alcohol selox, with initial rates for Pd/meso-Al2O 3 far exceeding those achievable for palladium over either amorphous alumina or mesoporous silica supports. Pd/meso-Al2O3 is exceptionally active for the atom efficient selox of diverse allylic alcohols, with activity inversely proportional to alcohol mass.
- Parlett, Christopher M.A.,Durndell, Lee J.,Wilson, Karen,Bruce, Duncan W.,Hondow, Nicole S.,Lee, Adam F.
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- Highly efficient and selective aerobic oxidation of alcohols in aqueous media by TEMPO-containing catalytic systems
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The use of molecular oxygen as the oxidant and water as reaction medium is a charming research orientation in the oxidation of alcohols. In this communication, the efficient aerobic oxidation of alcohols to the corresponding carbonyl compounds in aqueous media has been achieved with TEMPO-containing catalytic systems. In the absence of base/acid, a 99% conversion and 94% selectivity for benzaldehyde were obtained for the oxidation of benzyl alcohol by TEMPO-Ce(IV)-NaNO2 in water. Moreover, the effects of quaternary ammonium salts and anionic surfactants were investigated. The aerobic selective oxidation of different non-heterocyclic alcohols in aqueous media was further investigated, and the moderate to high yields (45.5-98.0%) of products were obtained.
- Yan, Yongtao,Tong, Xinli,Wang, Kaixuan,Bai, Xueqin
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p. 112 - 115
(2013/11/06)
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- Chemoselective hydrogen peroxide oxidation of allylic and benzylic alcohols under mild reaction conditions catalyzed by simple iron-picolinate complexes
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Chemoselective oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds proceeded efficiently using hydrogen peroxide with iron-picolinate catalysts. The in situ generated [Fe(Me-Pic)3] (Me-Pic = 6-methylpicolinate) catalyzed oxidation of the alcohol moiety of primary allylic alcohols while the [Fe(Pic)3] (Pic = picolinate) and [Fe(Me-Pic)2(Pic)] did not show sufficient catalytic activity. the Partner Organisations 2014.
- Tanaka, Shinji,Kon, Yoshihiro,Nakashima, Takuya,Sato, Kazuhiko
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p. 37674 - 37678
(2014/11/07)
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- Chemoselective hydrogen peroxide oxidation of allylic and benzylic alcohols under mild reaction conditions catalyzed by simple iron-picolinate complexes
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Chemoselective oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds proceeded efficiently using hydrogen peroxide with iron-picolinate catalysts. The in situ generated [Fe(Me-Pic)3] (Me-Pic = 6-methylpicolinate) catalyzed oxidation of the alcohol moiety of primary allylic alcohols while the [Fe(Pic)3] (Pic = picolinate) and [Fe(Me-Pic)2(Pic)] did not show sufficient catalytic activity. This journal is
- Tanaka, Shinji,Kon, Yoshihiro,Nakashima, Takuya,Sato, Kazuhiko
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p. 37674 - 37678
(2014/12/11)
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- Process for preparing 3-substituted 2-alkenals, in particular prenal
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The present invention to a process for preparing 2-alkenals of the formula I in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C10-aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl ; comprising dehydrogenating an alkenol of the formula II, an alkenol of the formula III or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol II or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
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Paragraph 0124
(2013/06/06)
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- PROCESS FOR PREPARING 3-SUBSTITUTED 2-ALKENALS, IN PARTICULAR PRENAL
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The present invention to a process for preparing 2-alkenals of the formula (I) in which R1 is selected from hydrogen and C1-C4-alkyl; and R2 is selected from hydrogen, C1-C12-alkyl, C2-C12-alkenyl, C4-C8-cycloalkyl and C6-C-10 aryl, wherein C1-C12-alkyl and C1-C12-alkenyl may be substituted with C5-C7-cycloalkyl or C5-C7-cylcoalkenyl; comprising dehydrogenating an alkenol of the formula (II), an alkenol of the formula (III) or a mixture thereof, wherein R1 and R2 are each as defined above, wherein the alkenol II, the alkenol III or a mixture thereof is brought into contact with a catalytic system comprising at least one ligand and a metal compound selected from ruthenium(II) compounds and iridium(I) compounds, and wherein the hydrogen formed during the dehydrogenation is removed from the reaction mixture by: i) reaction with a reoxidant selected from C3-C12-alkanones, C4-C9-cycoalkanones, benzaldehyde and mixtures thereof; and/or ii) purely physical means.
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Page/Page column 25
(2013/06/06)
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- One-pot, high-yield synthesis of one-dimensional ZnO nanorods with well-defined morphology as a highly selective photocatalyst
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One-dimensional (1D) semiconductor ZnO nanorods have been successfully prepared via a facile surfactant-free hydrothermal method. Their structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), UV-vis diffuse reflectance spectra (DRS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption, photoluminescence spectra (PL) and electron spin resonance spectra (ESR). It is found that ZnO nanorods with diameters around 20-30 nm and lengths up to several micrometers are well-distributed. ZnO nanorods have been used to photocatalyze the aerobic oxidation of alcohols to aldehydes under ambient conditions. The results show that ZnO nanorods exhibit a markedly enhanced photoactivity and selectivity compared to their precursor, commercial ZnO, which can be ascribed to the special 1D morphology of ZnO nanorods leading to its favorable, selective adsorptivity toward the reactant of alcohols instead of the product of aldehydes, and the efficient separation of photogenerated charge carriers. A possible reaction mechanism for the photocatalytic selective oxidation of alcohols over ZnO nanorods has also been proposed. Our present work not only provides a facile, high-yield and surfactant-free approach for the fabrication of ZnO nanorods, but also enriches the chemistry of morphology-dependent functional properties of ZnO materials in the application of heterogeneous photocatalytic selective oxidation, which therefore could open a new doorway to utilize 1D semiconductor materials such as nanorods, nanotubes and nanowires as photocatalysts in selective transformation under ambient conditions.
- Tang, Zi-Rong,Yin, Xia,Zhang, Yanhui,Xu, Yi-Jun
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p. 5956 - 5965
(2013/05/09)
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- Mesoporous Silicas as Versatile Supports to Tune the Palladium-Catalyzed Selective Aerobic Oxidation of Allylic Alcohols
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Surfactant templating offers a simple route to synthesize high-surface area silicas with ordered, tunable mesopore architectures. The use of these materials as versatile catalyst supports for palladium nanoparticles has been explored in the aerobic selective oxidation (selox) of allylic alcohols under mild conditions. Families of Pd/mesoporous silicas, synthesized through incipient wetness impregnation of SBA-15, SBA-16, and KIT-6, have been characterized by using nitrogen porosimetry, CO chemisorption, diffuse reflection infrared Fourier transform spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and high-resolution TEM and benchmarked in liquid phase allylic alcohol selox against a Pd/amorphous SiO2 standard. The transition from amorphous to two-dimensional parallel and three-dimensional interpenetrating porous silica networks conferred significant selox rate enhancements associated with higher surface densities of active palladium oxide sites. Dissolved oxygen was essential for insitu stabilization of palladium oxide, and thus maintenance of high activity on-stream, whereas selectivity to the desired aldehyde selox product over competing hydrogenolysis pathways was directed by using palladium metal.
- Parlett, Christopher M. A.,Bruce, Duncan W.,Hondow, Nicole S.,Newton, Mark A.,Lee, Adam F.,Wilson, Karen
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p. 939 - 950
(2013/06/04)
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- Redox-selective generation of aldehydes and H2 from alcohols under visible light
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Photosynthetic dehydrogenation: Potential usefulness of visible-light-induced dehydrogenation of alcohols in organic synthesis was demonstrated, in which aldehydes and H2 were afforded by using Ru/SrTiO3:Rh and water (see scheme). Water was essential for the reaction. High efficiency (TON: up to 15 400 based on Rh; H2 and aldehyde evenly generated) and high selectivity were achieved. Copyright
- Liu, Zijun,Caner, Joaquim,Kudo, Akihiko,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 9452 - 9456
(2013/07/26)
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- Multifunctional NH2-mediated zirconium metal-organic framework as an efficient visible-light-driven photocatalyst for selective oxidation of alcohols and reduction of aqueous Cr(vi)
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Metal-organic frameworks (MOFs) have been arousing a great interest owing to their unique physicochemical properties. In this work, Zr- benzenedicarboxylate (UiO-66) and its derivative, Zr-2-NH2- benzenedicarboxylate (UiO-66(NH2)), are successfully prepared via a facile solvothermal method and applied to photocatalytic reactions. Powder X-ray diffraction (XRD) confirms the isoreticular nature of UiO-66 and UiO-66(NH 2), while Fourier transformed infrared spectra (FTIR) prove the effective presence of amino group. UV-vis diffuse reflectance spectra (DRS) show the photoabsorption edge of UiO-66 could be shifted to the visible light region by simply introducing the amino group (-NH2) on the organic ligand. Importantly, UiO-66(NH2) is proved to perform as an efficient multifunctional visible-light-driven photocatalyst with high stability and considerable recyclability in both the photocatalytic selective oxidation of alcohols to aldehydes using molecular oxygen as oxidant and catalytic reduction of aqueous Cr(vi) to Cr(iii) under ambient conditions. Furthermore, the possible reaction mechanism has also been investigated in detail. This work makes a systematic attempt to understand the reaction of photocatalytic selective oxidation of alcohols over MOFs and represents the first example to report the identification of MOFs as promising visible-light photocatalysts toward reduction of aqueous Cr(vi). More significantly, our finding also provides a new way to design MOFs-based photocatalysts, that is, by tuning the predesigned ligands with specific functional groups, the optical absorption properties of MOFs can be flexibly modulated, and then the effective solar energy conversion can be expected.
- Shen, Lijuan,Liang, Shijing,Wu, Weiming,Liang, Ruowen,Wu, Ling
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p. 13649 - 13657
(2013/09/23)
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- Synthesis of titanate nanotube-CdS nanocomposites with enhanced visible light photocatalytic activity
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CdS-1D titanate nanotubes (CdS/TNTs) nanocomposites have been synthesized via a facile one-step in situ hydrothermal method. The structure and properties of CdS/TNTs nanocomposites have been characterized by X-ray diffraction, UV-vis diffuse reflectance spectra, transmission electron microscopy, photoluminescence spectra, nitrogen adsorption-desorption, and electron spin resonance spectra. The results show that (i) as compared to blank-CdS, it is found that the morphology of CdS in the CdS/TNTs nanocomposites can be finely tuned by TNTs formed during the one-step in situ hydrothermal process; and (ii) the CdS/TNTs nanocomposites exhibit remarkably much higher visible light photocatalytic activity than both blank-CdS and blank-TNT toward aerobic selective oxidation of alcohols under mild conditions. Three integrative factors lead to such a drastic photoactivity enhancement for CdS/TNTs nanocomposites. The first one is the different morphology of CdS in the CdS/TNTs nanocomposites from blank-CdS. The second one is the prolonged lifetime of photogenerated electron-hole pairs from CdS in CdS/TNTs nanocomposites under visible light irradiation. The third one is the higher surface area and adsorption capacity of CdS/TNTs nanocomposites than blank-CdS. In addition, the possible reaction mechanism for photocatalytic selective oxidation of alcohols over CdS/TNTs nanocomposites has also been investigated using the radical scavengers technique. It is hoped that this work could promote further interest in fabrication of various 1D TNT-based composite materials and their application to visible-light-driven photocatalytic selective organic transformations.
- Tang, Zi-Rong,Yin, Xia,Zhang, Yanhui,Xu, Yi-Jun
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p. 11758 - 11766
(2013/11/19)
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- Substrate specificity and subcellular localization of the aldehyde-Alcohol redox-Coupling reaction in carp cones
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Our previous study suggested the presence of a novel conespecific redox reaction that generates 11-cis-retinal from 11-cisretinol in the carp retina. This reaction is unique in that 1) both 11-cis-retinol and all-trans-retinal were required to produce 11-cis-retinal; 2) together with 11-cis-retinal, all-trans-retinol was produced at a 1:1 ratio; and 3) the addition of enzyme cofactors such as NADP(H) was not necessary. This reaction is probably part of the reactions in a cone-specific retinoid cycle required for cone visual pigment regeneration with the use of 11-cis-retinol supplied from Mueller cells. In this study, using purified carp cone membrane preparations, we first confirmed that the reaction is a redox-coupling reaction between retinals and retinols. We further examined the substrate specificity, reaction mechanism, and subcellular localization of this reaction. Oxidation was specific for 11-cis-retinol and 9-cis-retinol. In contrast, reduction showed low specificity: many aldehydes, including all-trans-, 9-cis-, 11-cis-, and 13-cis-retinals and even benzaldehyde, supported the reaction. On the basis of kinetic studies of this reaction (aldehyde-alcohol redox-coupling reaction), we found that formation of a ternary complex of a retinol, an aldehyde, and a postulated enzyme seemed to be necessary, which suggested the presence of both the retinol- and aldehydebinding sites in this enzyme. A subcellular fractionation study showed that the activity is present almost exclusively in the cone inner segment. These results suggest the presence of an effective production mechanism of 11-cis-retinal in the cone inner segment to regenerate visual pigment.
- Sato, Shinya,Fukagawa, Takashi,Tachibanaki, Shuji,Yamano, Yumiko,Wada, Akimori,Kawamura, Satoru
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p. 36589 - 36597
(2014/01/17)
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