Regio-and Stereoselective Synthesis of(Z)-3-Ylidenephthalides via H_(3)PMo1_(2)O_(40)-Catalyzed Cyclization of 2-Acylbenzoic Acids with Benzylic Alcohols

We report an exclusively tandem C—O and C—C bond forming beyond the esterification and cyclization reaction of 2-acylbenzoic acids with alcohols to regio-and stereoselective synthesis of the(Z)-3-ylidenephthalides.The reaction uses the nontoxic,inexpensive H_(3)PMo1_(2)O_(40) as catalyst and produces water as the sole by-product,making the reaction environmentally benign and sustainable.Moreover,this reaction features an eco-friendly reaction condition,facile scalability,and easy derivatization of the products to drugs and bioactive compounds.The mechanism studies and density functional theory calculations reveal that the appropriate acid catalyst is the key to the selectivity of this transformation.

Development of Highly Effective Nanoparticle Spinel Catalysts for Aerobic Oxidation of Benzylic Alcohols

Spinel catalyst MnFe 1.8Cu 0.15Ru 0.05O 4 with particle size of about 42 nm is an effective heterogeneous catalyst for the oxidation of benzylic alcohols. The substitution of Fe for Cu improves its catalytic activity. Based on the characterization of BET, XPS and EXAFS, two factors influencing the structure and texture of the catalyst caused by the substitution of Cu for Fe may be assumed: physical factor responsible for the increasing of surface area; chemical factor responsible for the transformation of Ru-O bonds to Ru=O bonds. β-Elimination is considered to be an important step in the reaction.

A novel and selective oxidation of benzylic alcohols with polymer-supported periodic acid under mild aprotic conditions

A new polymeric oxidizing reagent was prepared by supporting periodic acid on poly（1,4-phenylene-2,5-pyridine dicarboxyamide）. This polymeric reagent was used for the selective oxidation of primary benzylic alcohols to the corresponding benzaldehydes in CH_3CN at reflux conditions.Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions.Allylic alcohols were also converted to the corresponding aldehydes with good yields.

Solvent-free alkylation of dimethyl malonate using benzyl alcohols catalyzed by FeCl_3/SiO_2

Activated methylene compound such as dimethyl malonate reacted readily with benzylic alcohols in the presence of ferric chloride/silica gel mixture （FeCl3/SiO2） under microwave irradiation to produce benzylic derivative of dimethyl malonate in high yields in solvent-free condition. 2009 Mohammad Reza Shushizadeh. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Oxidation of benzyl alcohols to ketones and aldehydes by O3 process enhanced using high-gravity technology

In this study,a practical process for ozonization of benzyl alcohols to ketones and aldehydes in a rotating packed bed(RPB-O3)reactor has been developed.Using 1-phenylethanol as a model reactant,the performance of RPB-O3 process in different solvents has been compared with the commonly used stirred tank reactor(STR-O3).Ethyl acetate was the optimum solvent for the conversion of 1-phenylenthanol to acetophenone in RPB-O3 process,with 78%yield after 30 min.In a parallel STR-O3 experiment,the yield of acetophenone was50%.Other experimental variables,i.e.O3 concentration,reaction time,high-gravity factor and liquid flow rate were also optimized.The highest yield of acetophenone was obtained using O3 concentration of 80 mg·L-1,reaction time of 30 min,high gravity factor of 40 and liquid flow rate of 120 L·h-1.Under the optimized reaction conditions,a series of structurally diverse primary and secondary alcohols was oxidized with(19%–92%)yield.The ozonization mechanism was studied by Electron Paramagnetic Resonance(EPR)spectroscopy,monitoring the radical species formed upon self-decomposition of O3.The characteristic quadruple peak with the 1:2:2:1 intensity ratio that corresponds to hydroxyl radicals(·OH)was observed in the electron paramagnetic resonance(EPR)spectrum,indicating an indirect oxidation mechanism of alcohols via·OH radical.

CaY-zeolite Catalyzed Etherification and Alkylation of Substituted Benzyl Alcohols

The reaction of p- and/ α-subtituted benzyl alcohols in CaY-zeolite produced the corresponding dibenzyl ethers and/or benzyl toluenes as the principal products.

Different efficiency toward the biomimetic aerobic oxidation of benzyl alcohol in microchannel and bubble column reactors: Hydrodynamic characteristics and gas–liquid mass transfer

The selective aerobic oxidation of benzyl alcohol to benzaldehyde has attracted considerable attention because benzaldehyde is a high value-added product. The rate of this typical gas–liquid reaction is significantly affected by mass transfer. In this study, CoTPP-mediated(CoTPP: cobalt(II) mesotetraphenylporphyrin) selective benzyl alcohol oxidation with oxygen was conducted in a membrane microchannel(MMC) reactor and a bubble column(BC) reactor, respectively. We observed that 83% benzyl alcohol was converted within 6.5 min in the MMC reactor, but only less than 10% benzyl alcohol was converted in the BC reactor. Hydrodynamic characteristics and gas–liquid mass transfer performances were compared for the MMC and BC reactors. The MMC reactor was assumed to be a plug flow reactor,and the dimensionless variance was 0.29. Compared to the BC reactor, the gas–liquid mass transfer was intensified significantly in MMC reactor. It could be ascribed to the high gas holdup(2.9 times higher than that of BC reactor), liquid film mass transfer coefficient(8.2 times higher than that of BC reactor), and mass transfer coefficient per unit interfacial area(3.8 times higher than that of BC reactor). Moreover,the Hatta number for the MMC reactor reached up to 0.61, which was about 15 times higher than that of the BC reactor. The computational fluid dynamics calculations for mass fractions in both liquid and gas phases were consistent with the experimental data.

Biotransformation of Gastrodin by Mucor spinosus

Microbial transformation of gastrodin by Mucor spinosus strain 3.3450, resulted in a product with a transformation rate close to 100 per cent. This product was identified as p-hydroxy benzyl alcohol on the basis of its 1H, 13C NMR and EI-MS spectral data. It could be inferred that the enzyme responsible for the biotransforma-tion reaction was a kind of extracellular and constitutive enzyme since the transformation reaction of the substrate could be carried out in cell free extracts of the fermentation broth of the Mucor spinosus.

Catalytic Performance of MnOx Nanorods in Aerobic Oxidation of Benzyl Alcohol

Various manganese oxide nanorods with similar one-dimensional morphology were prepared by calcination of MnOOH nanorods under different gas atmosphere and at different temper- atures, which were synthesized by a hydrothermal route. The morphology and structure of MnOx catalysts were characterized by a series of techniques including X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and tempera- ture programmed reduction （TPR）. The catalytic activities of the prepared MnO~ nanorods were tested in the liquid phase aerobic oxidation of benzyl alcohol, which follow a sequence as MnO2〉Mn203~Mn304〉MnOOH with benzaldehyde being the main product. On the basis of H2-TPR results, the superior activity of MnO2 is ascribed to its lower reduction temperature and therefore high oxygen mobility and excellent redox ability. Moreover, a good recycling ability was observed over MnO2 catalysts by simply thermal treatment in air.

Efficient oxidation of benzyl alcohol with heteropolytungstate as reaction-controlled phase-transfer catalyst

A series of heteropolytungstates has been synthesized and utilized as catalysts to catalyze oxidation of benzyl alcohol with aqueous hydrogen peroxide. The results indicated that three of these catalysts showed the properties of reaction-controlled phasetransfer catalysis, and they had excellent catalytic ability to the oxidation of benzyl alcohol. No other by-products were detected by gas chromatography. Once the hydrogen peroxide was consumed completely, the catalyst precipitated from solvent, and the results of the catalyst recycle showed that the catalyst had high stability.

Selective suppression of toluene formation in solvent-free benzyl alcohol oxidation using supported Pd-Ni bimetallic nanoparticles

The solvent‐free oxidation of benzyl alcohol was studied using supported Pd‐Ni bimetallic nanoparticles.Compared with monometallic Pd,the addition of Ni to Pd was found to be effective in suppressing the nondesired product toluene,thereby enhancing the selectivity towards benzaldehyde.This result was attributed to a dual effect of Ni addition:the weakening of dissociative adsorption of benzyl alcohol and the promotion of oxygen species involved in the oxidation pathway.

Aerobic Oxidation of Benzyl Alcohol Catalyzed by Cu-Mn Mixed Oxides and 2,2,6,6-Tetramethyl-piperidyl-1-oxyl

Heterogeneous Cu-Mn mixed oxides can mediate TEMPO-catalyzed selective oxidation of benzyl alcohol by molecular oxygen under neutral condition, and is recyclable. In the case of the molar ratio of Cu and Mn over 1, the highly-dispersed CuO inside the Cu-Mn mixed oxides is responsible for the good performances in catalytic oxidation.

The Role of Vanadia for the Selective Oxidation of Benzyl Alcohol over Heteropolymolybdate Supported on Alumina

A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support. In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.

镍铁氰化物纳米粒子的合成及其多相催化无溶剂条件下苯甲醇氧化的潜能(英文)

Nickel hexacyanoferrate nanoparticles were synthesized and characterized using elemental analysis, thermal analysis, infrared spectroscopy, and X-ray diffraction. A FE-SEM image of the nickel hexacyanoferrate showed that it consists of nearly spherical particles with sizes ranging from 30 to 70 nm. The synthesized material was found to be a heterogeneous catalyst useful for the solvent-free oxidation of benzyl alcohol with H2O2 as an oxidant. A 36% conversion of benzyl alcohol to benzaldehyde was achieved under optimized reaction conditions using specific parameters such as the amount of catalyst, the temperature, the benzyl alcohol to H2O2 molar ratio, and the reaction time.

Syntheses and Application of New Room Temperature Ionic Liquids Based on Hexaalkylguanidinium Salts

A new series of guanidinium cation-based room temperature ionic liquids(RTILS) was prepared by treating tetraalkylguanidine with an alkylating agent in the presence of an alkaline reagent and a phase transfer catalyst(PTC). Good results were obtained when GPF_6 was used as the reaction medium for the selective oxidation of benzyl alcohol with sodium hypochlorite as the oxidant.

Photocatalytic oxidation of primary and secondary benzyl alcohol catalyzed by two coenzyme NAD^+ models

Photocatalytic oxidation of primary and secondary benzyl alcohol to corresponding benzaldehyde or acetophenone using Acr＋Cl04- or PhAcr＋Cl04- as photocatalysts under visible light irradiation at room temperature.

Site-specific deposition creates electron-rich Pd atoms for unprecedented C-H activation in aerobic alcohol oxidation

Here,we demonstrate a photochemical strategy to site-specifically deposit Pd atoms on Au nanoparticles.The high-sensitivity low-energy ion scattering spectra combined with the X-ray photoelectron spectra reveal that the surface electronic structure of Pd can be continuously regulated by tailoring the Pd-to-Au molar ratio and the location of Pd atoms in Au Pd nanoparticles.It is revealed that electron-rich Pd atoms are considerably more active than the net Pd atoms in aerobic alcohol oxidation.Remarkably,the catalyst with the most electron-rich Pd sites(binding energy downshift:1.0 e V)exhibits an extremely high turnover frequency(~500000 h-1 vs 12000 h-1 for that with net Pd atoms)for solvent-free selective oxidation of benzyl alcohol,which is,to the best of our knowledge,the highest value ever reported.Kinetic studies reveal that electron-rich Pd atoms can accelerate the oxidation of benzyl alcohol by facilitating C-H cleavage,as indicated by the significant reduction in the activation energy as compared to net Pd atoms.

Selectivity modulation in the consecutive hydrogenation of benzaldehyde via functionalization of carbon nanotubes

Hydrogenation of benzaldehyde is a typical consecutive reaction, since the intermediate benzyl alcohol is apt to be further hydrogenated. Here we demonstrate that the selectivity of benzyl alcohol can be tuned via functionalization of carbon nanotubes （CNTs）, which are used as the support of Pd. With the original CNTs, the selectivity of benzyl alcohol is 88% at a 100% conversion of benzaldehyde. With introduction of oxygen-containing groups onto CNTs, it drops to 27%. In contrast, doping CNTs with N atoms, the selectivity reaches 96% under the same reaction conditions. The kinetic study shows that hydrogenation of benzyl alcohol is significantly suppressed, which can be attributed to weakened adsorption of benzyl alcohol. This is most likely related to the modified electronic structure of Pd species via interaction with functionalized CNTs, as shown by XPS characterization.

Morphology-dependent structures and catalytic performances of Au nanostructures on Cu_2O nanocrystals synthesized by galvanic replacement reaction

Au nanostructures were prepared on uniform Cu2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAuCl 4 and Cu2O. The compositions and structures were studied by Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), High-Resolution Transmission Electron Microscope (HRTEM), X-Ray Diffraction (XRD), X-Ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS) and in-situ DRIFTS spectroscopy of CO adsorption. Different from the formation of Au-Cu alloys on Cu2O cubes by the galvanic replacement reaction (ChemNanoMat 2 (2016) 861-865), metallic Au particles and positively-charged Au clusters form on Cu2O octahedra and rhombic dodecahedra at very small Au loadings and only metallic Au particles form at large Au loadings. Metallic Au particles on Cu2O octahedra and rhombic dodecahedra are more active in catalyzing the liquid phase aerobic oxidation reaction of benzyl alcohol than positively-charged Au clusters. These results demonstrate an obvious morphology effect of Cu2O nanocrystals on the liquid-solid interfacial reactions and prove oxide morphology as an effective strategy to tune the surface reactivity and catalytic performance. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Weak base favoring the synthesis of highly ordered V-MCM-41 with well-dispersed vanadium and the catalytic performances on selective oxidation of benzyl alcohol

The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of heteroatoms.The alkalinity plays the indispensable role in synthetic process of V-MCM-41 catalyst.The excessive alkalinity of synthetic system will make the MCM-41 difficult to crystallize,even to dissolve.It is easy to accumulate for heteroatomic species in the system of low alkalinity.Herein,the highly ordered VMCM-41 with high vanadic content in framework is synthesized in the condition of excessive NH3·H2 O in this paper.A series of characterization results prove the good dispersion of vanadium species,and most of vanadium gets into the framework of MCM-41 with the states of tetravalence and pentavalence.Furthermore,the modified MCM-41 by other transition metals is successful synthesized by the method of V-MCM-41 in this paper.The VMCM-41 shows well catalytic activity for the selective oxidation of benzyl alcohol,which up to 74.83%for the conversion of benzyl alcohol and 96.20%for selectivity of benzaldehyde when initial V/Si=0.10.The paper provides the possibility for industrial application of V-MCM-41 in the oxidation of benzyl alcohol for benzaldehyde.Besides,the work provides a significant idea for the synthesis of modified MCM-41 by well-dispersed transition metals.