Showing papers on "Benzaldehyde published in 2015"
TL;DR: The role of lattice oxygen on the activity and selectivity of the OMS-2 catalyst synthesized by the hydrothermal method was investigated for the catalytic oxidation of toluene.
326 citations
TL;DR: In this article, a series of mixed-linker zirconium-based metal-organic frameworks (Zr-MOFs) have been synthesized in one-pot reactions.
102 citations
TL;DR: Two novel dimethylphenyl imidazole dicarboxylate-based lanthanide(III)-organic frameworks, synthesized under hydrothermal conditions, indicate characteristic sharp emission bands of Eu(3+) or Tb(3%) ions, which are selectively sensitive to benzaldehyde-based derivatives.
Abstract: Two novel dimethylphenyl imidazole dicarboxylate-based lanthanide(III)-organic frameworks, [Ln(H2DMPhIDC)3(H3DMPhIDC)]n (Ln = Eu (1), Tb (2); H3DMPhIDC = 2-(3,4-dimethylphenyl)-1H-imidazole-4,5-dicarboxylic acid) have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction analyses revealed that polymers 1 and 2 crystallize in the tetragonal space group I41 and exhibit isostructural three-dimensional (3D) solid-state frameworks. Both complexes indicate characteristic sharp emission bands of Eu3+ or Tb3+ ions, which are selectively sensitive to benzaldehyde-based derivatives (benzaldehyde, m-methylbenzaldehydes, m-carboxylbenzaldehyde and m-hydroxybenzaldehyde). These properties make both complexes potential fluorescence sensors for these chemicals.
91 citations
TL;DR: This study suggests, for the first time, that species with an open metal site like adducts [nanoparticle-M]((z-1)+) or fragments Au25-n(SR)18-n function as the catalysts rather than the intact Au25( SR)18.
Abstract: The catalytic activity of Au25(SR)18 nanoclusters (R = C2H4Ph) for the aldehyde hydrogenation reaction in the presence of a base, e.g., ammonia or pyridine, and transition-metal ions Mz+, such as Cu+, Cu2+, Ni2+ and Co2+, as a Lewis acid is studied. The addition of a Lewis acid is found to significantly promote the catalytic activity of Au25(SR)18/CeO2 in the hydrogenation of benzaldehyde and a number of its derivatives. Matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry in conjunction with UV–vis spectroscopy confirm the generation of new species, Au25-n(SR)18-n (n = 1–4), in the presence of a Lewis acid. The pathways for the speciation of Au24(SR)17 from its parent Au25(SR)18 nanocluster as well as its structure are investigated via the density functional theory (DFT) method. The adsorption of Mz+ onto a thiolate ligand “—SR—” of Au25(SR)18, followed by a stepwise detachment of “—SR—” and a gold atom bonded to “—SR—” (thus an “Au-SR” unit) is found to...
90 citations
TL;DR: The high sensitivity and selectivity of the luminescence response of 1 to benzaldehyde allows it to be used as an excellent sensor for identifying benzaldehyde and provides a simple and convenient method for detecting traces of benzaldehyde in benzyl alcohol based injections.
Abstract: Luminescent 3D lanthanide metal-organic framework (Ln-MOF) {[Tb2 (TATAB)2 ]⋅4 H2 O⋅6 DMF}n (1) was synthesized under solvothermal conditions by using flexible ligand 4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB). A phase transition was observed between low temperature and room temperature. The luminescence of 1 could be enhanced by formaldehyde and quenched efficiently by trace amounts of benzaldehyde in solvents such as benzyl alcohol (0.01-2.0 vol %) and ethanol (0.01-2.5 vol %). This is the first use of a Ln-MOF as chemical sensor for both formaldehyde and benzaldehyde. The high sensitivity and selectivity of the luminescence response of 1 to benzaldehyde allows it to be used as an excellent sensor for identifying benzaldehyde and provides a simple and convenient method for detecting traces of benzaldehyde in benzyl alcohol based injections. This work establishes a new strategy for detection of benzaldehyde in benzyl alcohol by luminescent MOFs.
88 citations
TL;DR: An oxygenation reaction with a 100% theoretical atom economy using a polyoxometalate oxygen donor has been found and the product yield is typically above 95% with no "overoxidation" to benzoic acids.
Abstract: The synthesis of benzaldehyde derivatives by oxygenation of methylarenes is of significant conceptual and practical interest because these compounds are important chemical intermediates whose synthesis is still carried out by nonsustainable methods with very low atom economy and formation of copious amounts of waste. Now an oxygenation reaction with a 100% theoretical atom economy using a polyoxometalate oxygen donor has been found. The product yield is typically above 95% with no “overoxidation” to benzoic acids; H2 is released by electrolysis, enabling additional reaction cycles. An electrocatalytic cycle is also feasible. This reaction is possible through the use of an aqueous sulfuric acid solvent, in an aqueous biphasic reaction mode that also allows simple catalyst recycling and recovery. The solvent plays a key role in the reaction mechanism by protonating the polyoxometalate thereby enabling the activation of the methylarenes by an electron transfer process. After additional proton transfer and ox...
76 citations
TL;DR: In this paper, the role of molecular oxygen in the photocatalytic process of benzaldehyde was investigated and molecular oxygen was not incorporated into the final benzaldehyde and only involved in the oxidation of Cu(I) into Cu(II) in which it served as a terminal hydrogen acceptor to form H2O.
Abstract: The oxidation of alcohols to the corresponding carbonyl compounds is a pivotal reaction in organic synthesis. Under visible light irradiation, the homogeneous CuCl2 and cheap solvent oxidized benzyl alcohol into benzaldehyde with a selectivity higher than 95% using molecular oxygen as an oxidant. The formation of a visible light responsive complex between Cu(II) and solvent is responsible for the occurrence of the oxidation of benzyl alcohol. During the photocatalytic process, molecular oxygen was not incorporated into the final benzaldehyde and only involved in the oxidation of Cu(I) into Cu(II) in which it served as a terminal hydrogen acceptor to form H2O. A similar role of molecular oxygen has also been observed in the heterogeneous TiO2 photocatalytic system. The understanding of the role of molecular oxygen helps us to further design new classes of synthetic organic reactions by photocatalytic processes.
71 citations
TL;DR: It was found that the Au and small CeO 2 nanoparticles were homogeneously mixed in the channels of SBA-15, which led to an increase in the interfacial area between Au and CeO2 and consequently a better catalytic performance of Au-CeO2@SBA- 15 catalysts for the selective oxidation of benzyl alcohol to benzaldehyde.
Abstract: Tuning the interfacial perimeter and structure is crucial to understanding the origin of catalytic performance. This paper describes the design, characterization, and application of CeO2 modified Au@SBA-15 (Au–CeO2@SBA-15) catalysts in selective oxidation of benzyl alcohol. The reaction results showed that Au–CeO2@SBA-15 catalysts exhibited higher catalytic activity compared with Au@SBA-15 and Au/CeO2 catalysts under identical conditions along with the high selectivity towards benzaldehyde (>99%). The turnover frequency of benzyl alcohol over the Au–100CeO2@SBA-15 catalyst is about nine-fold and four-fold higher than those of Au@SBA-15 and Au/CeO2 catalysts, respectively. The supported catalysts were characterized by N2 adsorption–desorption, inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, scanning transmission electron microscopy-energy dispersive spectrometry, and X-ray photoelectron spectroscopy. It was found that the Au and small CeO2 nanoparticles (∼5 nm) were homogeneously mixed in the channels of SBA-15, which led to an increase in the interfacial area between Au and CeO2 and consequently a better catalytic performance of Au–CeO2@SBA-15 catalysts for the selective oxidation of benzyl alcohol to benzaldehyde compared with that of Au/CeO2. The prevention of agglomeration and leaching of Au nanoparticles by restricting them inside the mesopores of SBA-15 was conducive to the stable existence of large quantities of Au–CeO2 interface, which leads to high stability of the Au–CeO2@SBA-15 catalyst.
68 citations
TL;DR: The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters.
Abstract: The stoichiometric use of hydrogen peroxide in the presence of a selenium-containing catalyst in water is here reported as a new ecofriendly protocol for the synthesis of variously functionalized carboxylic acids and esters. The method affords the desired products in good to excellent yields under very mild conditions starting directly from commercially available aldehydes. Using benzaldehyde as a prototype the gram scale synthesis of benzoic acid is described, in which the aqueous medium and the catalyst could be recycled at last five times while achieving an 87% overall yield.
66 citations
TL;DR: In this paper, a comparative study of the structural, optical and catalytic properties of CoAl 2 O 4 nanoparticles is reported, where cobalt aluminate nano and microstructures were synthesized by both conventional and microwave methods using Sesame (Sesamum indicum, L.,) as a plant extract.
64 citations
TL;DR: In this article, a new synthesis strategy has been developed to synthesize exclusively (100)-surface-exposed CeO2 nanocubes (∼90 nm), formed through three dimensional (3D) self-assembly of smaller ceria nanocrystal building blocks, as an efficient heterogeneous catalyst for multiple selective oxidation reactions.
Abstract: A new synthesis strategy has been developed to synthesize exclusively (100)-surface-exposed CeO2 nanocubes (∼90 nm), formed through three dimensional (3D) self-assembly of smaller ceria nanocrystal building blocks, as an efficient heterogeneous catalyst for multiple selective oxidation reactions. To compare the effect of morphology on catalysis, 1D CeO2 nanorods have also been tested in parallel. The as-synthesized CeO2 nanocubes acted as a breakthrough catalyst in the quantitative conversion of benzyl alcohol and para-chlorobenzyl alcohol with absolute selectivity to their respective aldehydes (>99%) under very mild reaction conditions in water at 35 °C. The same ceria nanocubes acted as an efficient catalyst in the oxidation of toluene to benzaldehyde selectively. The preferentially exposed (100) surfaces, the presence of a high concentration of oxygen vacancies (2.11 × 1021 cm−3), the small size of the nanoscale building blocks and the corresponding high surface area and porosity have been reasoned to produce the observed high catalytic activity parameter and turn over frequency (TOF). Further characterization of the recovered catalysts after five cycles confirmed the retention of the original morphology, crystal structure and, most importantly, catalytic properties with no significant activity loss, confirming the possibility of repeated use of the present CeO2 nanocubes without compromising their intrinsic qualities.
TL;DR: Kinetic analysis and reaction profile fitting of both the forward and reverse reactions, plus onwards reaction to the Breslow intermediate, demonstrate the remarkable effect of the benzaldehyde 2-substituent in these reactions and provide insight into the chemoselectivity of cross-benzoin reactions.
Abstract: Rate and equilibrium constants for the reaction between N-aryl triazolium N-heterocyclic carbene (NHC) precatalysts and substituted benzaldehyde derivatives to form 3-(hydroxybenzyl)azolium adducts under both catalytic and stoichiometric conditions have been measured. Kinetic analysis and reaction profile fitting of both the forward and reverse reactions, plus onwards reaction to the Breslow intermediate, demonstrate the remarkable effect of the benzaldehyde 2-substituent in these reactions and provide insight into the chemoselectivity of cross-benzoin reactions.
TL;DR: In this article, four recently launched cyclic glycerol acetals or ketals are evaluated as bio-based solvents and their solvent properties are evaluated through Hansen and COSMO-RS (COnductor-like Screening MOdel for Real Solvents) approaches.
TL;DR: In this paper, an iron-chloride immobilized ionic liquid (SIL-FeCl 3 ) was prepared by N-methylimidazole reacting with chloropropylsilane linked on the mesoporous silica SBA-15 and coordinating of FeCl 3 to the imidazolium chloride grafted on the surface.
TL;DR: In this article, an ECH-modified Fe3O4 microsphere was found to significantly enhance the catalytic activity of the microspheres in the selective oxidation of benzyl alcohol to benzaldehyde with H2O2 (yield: 8% vs. 34% before and after modification by ECH, respectively).
Abstract: Epichlorohydrin (ECH)-modified Fe3O4 microspheres were prepared in ethylene glycol by either in situ or post-synthetic modification and characterized via XRD, SEM, FTIR and VSM techniques. Modification by ECH was found to significantly enhance the catalytic activity of Fe3O4 microspheres in the selective oxidation of benzyl alcohol to benzaldehyde with H2O2 (yield: 8% vs. 34% before and after modification by ECH, respectively). Fe3O4 microspheres were magnetically recoverable and reusable at least five times without loss of catalytic activity and selectivity after being rejuvenated by a combined activation procedure comprising NaBH4 reduction and ECH modification. Theoretical and experimental investigations confirmed that the ECH-modification promoted the adsorption and decomposition of H2O2 on Fe3O4 microspheres via hydrogen bonding and facilitated the formation of hydroxyl radicals by increasing the collision frequency between H2O2 and Fe3O4 by about 10 orders of magnitude, which contributed to much better catalytic activity of ECH-modified Fe3O4 microspheres.
TL;DR: Through systematic deletion of competing aromatic amino acid biosynthesis pathways to promote endogenous phenylpyruvate availability, final benzyl alcohol titers as high as 114±1 mg/L were realized, representing a yield of 7.6±0.1mg/g on glucose and a ~5-fold improvement over initial strains.
TL;DR: Au25(SPh-pNH2)17 clusters on mesoporous silica SBA-15 (mean particle size 0.9 ± 0.2 nm) have been used as catalysts in the oxidation of benzyl alcohol.
TL;DR: In this paper, a tripodal tridentate copper(II) complex is synthesized to mimic the active site of copper enzymes that mediate the oxidation of aliphatic C-H bonds under mild condition.
TL;DR: Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene.
Abstract: A series of oxometallic species and metal acetylacetonates (acac) was examined as catalysts for oxidative carbonylation of styrene with benzaldehyde using t-butylhydroperoxide as the co-oxidant in warm acetonitrile. Among them, VO((acac)2 and vanadyl(IV) chloride were found to be the only catalyst class to achieve cross-coupling processes by judiciously tuning the ligand electronic attributes, leading to β-hydroxylation- and β-peroxidation-carbonylation of styrene, respectively, in a complementary manner. Mechanistic studies indicated that vanadyl-associated acyl radicals generated by t-butoxy radical-assisted, homolytic cleavage of the aldehyde C-H bond were involved in tandem processes with an exclusive syn diastereoselectivity in the case of β-methylstyrene.
TL;DR: In this paper, the transition metal-catalyzed oxidation of methylarenes is discussed, and the target products are benzaldehyde, benzoic acid, benzyl alcohol, etc.
Abstract: Oxidation is one of the fundamental transformations in organic synthesis. The selective oxidation of inert substrates is interesting and important. In this review, the transition metal-catalyzed oxidation of methylarenes is discussed. Benzaldehyde, benzoic acid, benzyl alcohol, etc., were produced as the target products. Copyright © 2014 John Wiley & Sons, Ltd.
TL;DR: In this paper, the performance of 6 wt% MnOx/SBA-15 catalysts with different manganese content was studied for the selective oxidation of toluene by oxygen under solvent-free conditions.
TL;DR: In this article, a post-synthesis grafting method combined with electroless deposition of Pd was used to obtain monolayer 3-aminopropyltriethoxysilane (APTES) grafting.
TL;DR: In this paper, a mixed-node MOF catalyst Ag-Cu-BTC was prepared by postsynthetic exchange (PSE) method, which can realize isomorphous replacement of Ag ion to framework Cu ion in Cu-BTC successfully.
01 Jan 2015
TL;DR: Theoretical study on the catalytic oxidation of benzyl alcohol by molecular oxygen (O2) on the TiO2 surface was performed by DFT calculations as mentioned in this paper, and it was clearly demonstrated that surface hydroxyl groups played a significant role in the formation of the alkoxide ([Ti]OCH2−ph) species.
Abstract: Theoretical study on the catalytic oxidation of benzyl alcohol by molecular oxygen (O2) on the TiO2 surface was performed by DFT calculations. The anatase TiO2 crystal faces in the absence and presence of surface hydroxyl groups were modeled with a slab of Ti16O32 and Ti16O32(OH)H, respectively. The interaction of benzyl alcohol with Ti16O32 and Ti16O32(OH)H was calculated. It was clearly demonstrated that the surface hydroxyl groups on the TiO2 surface play a significant role in the formation of the alkoxide ([Ti]OCH2−ph) species. The orbitals of the alkoxide species was found to be hybridized with the O2p orbital in the valence band (VB) of the TiO2. The origin of the visible-light response in the photocatalytic system can be attributed to the electronic transition from the donor levels created by the alkoxide species to the conduction band (CB). Furthermore, reaction coordinates in the overall catalytic reaction of benzyl alcohol into benzaldehyde on the TiO2 surface were demonstrated, and the role of the visible-light irradiation was also discussed.
TL;DR: The capacity of 100 yeast strains - isolated from grape musts and wines from the Istituto Sperimentale per l'Enologia collection - to produce benzaldehyde, benzyl alcohol and benzoic acid was verified by inoculation into a synthetic nutrient medium (MNS) as mentioned in this paper.
Abstract: The capacity of 100 yeast strains - isolated from grape musts and wines from the Istituto Sperimentale per l'Enologia collection - to produce benzaldehyde, benzyl alcohol and benzoic acid was verified by inoculation into a synthetic nutrient medium (MNS). Schizosaccharomyces and Zygosaccharomyces were strongest in producing benzaldehyde (maximal amount found 1200 µg/l) and benzyl alcohol (maximally 523 µg/l). Zygosaccharomyces was also most effective in the production of benzoic acid (maximally 536 µg/l), followed by Saccharomyces, Cryptococcus, Kloeckera and Torulaspora. The hypothesis was verified that yeasts can be an exogenous source of the benzyl alcohol oxidizing enzyme in grape musts and wines. Wine yeast strains of Saccharomyces spp., Zygosaccharomyces spp. and Schizosaccharomyces spp. fermenting MNS containing 150 g/l glucose, with benzyl alcohol added, transformed this into benzoic acid only when glucose was disappearing, but not into benzaldehyde. No difference was observed between aerobic and anaerobic fermentation conditions. The uptake of benzyl alcohol was rapid in fermentation essays in presence of only 10 g/l glucose and in assimilation essais performed in yeast nitrogen base broth with assimilable carbon compounds added. A catabolic repression by glucose appears likely. Botrytis cinerea was able to transform benzyl alcohol into benzaldehyde and benzoic acid on Czapek-Dox broth with 30 g/l sucrose added. Benzyl alcohol was transformed by wine yeasts into benzoic acid when the concentration of glucose in the mineral medium was less than 10 g/l, but no production of benzaldehyde was observed. A catabolic repression of this transformation by glucose is likely. Botrytis cinerea was able to produce benzaldehyde in a mineral medium with benzyl alcohol and sucrose added.
TL;DR: In this paper, the synthesis of tetrahydropyran compounds with 6-membered oxygen-containing heterocycles was investigated by using different parent zeolites as well as their metal modified forms and mesoporous materials.
Abstract: Tetrahydropyrans, compounds with 6-membered oxygen-containing heterocycles, are widely used for the synthesis of biologically active compounds with analgesic, anti-inflammatory or cytotoxic activity. Synthesis of compounds with the desired structure can be realized by several methods, including the acidic catalyzed Prins cyclization of homoallylic alcohol with simple aldehydes. In the current study, synthesis of compounds with the desired tetrahydropyran framework by Prins cyclization of benzaldehyde and alcohols with different structure, namely isopulegol and 3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol, was investigated. Different parent zeolites as well as their metal modified forms and mesoporous materials were employed in the comparative investigation. Activity and selectivity of the tested catalysts were correlated with their physico-chemical properties. The highest conversion and selectivity toward the product with the tetrohydropyran structure was achieved using Ce-MCM-41 in the interactions of isopulegol and benzaldehyde.
TL;DR: In this article, a metal-free system composed of mesoporous graphitic carbon nitride (mpg-C3N4) and N-hydroxyphthalimide (NHPI) was proposed for the oxidation of alcohols at room temperature.
TL;DR: A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB) was synthesized using cheap precursors and systematically characterized and the selective oxidation of toluene proceeded very smoothly over the catalyst.
Abstract: A novel Cu and boron doped graphitic carbon nitride catalyst (Cu-CNB) was synthesized using cheap precursors and systematically characterized. The selective oxidation of toluene proceeded very smoothly over the catalyst at 70 °C using tert-butyl hydroperoxide (TBHP) as the oxidant to exclusively afford benzaldehyde. The catalyst can be used for at least five cycles without decrease in activity and selectivity.
TL;DR: In this paper, the synthesis of novel bis(thiazoles) 19, 22, 24, 25, 30 and 31 is reported, where the bis(α-bromoketones) 14 and 15 with the corresponding thioamide derivatives 16 and 18 in refluxing EtOH in the presence of triethylamine afforded 19−22 in good yields.