Aerobic Oxidation Of Aromatic Alcohols Research Articles

Facile synthesis of CoSi alloy catalysts with rich vacancies for base- and solvent-free aerobic oxidation of aromatic alcohols

The rational design and green synthesis of low-cost, robust, and efficient catalysts for the selective oxidation of various alcohols are highly challenging. Herein, we report a fast and solvent-free arc-melting (AM) method to controllably synthesize a semimetallic CoSi alloy catalyst (denoted as AM-CoSi) that is efficient in the base- and solvent-free oxidation of six types of aromatic alcohols. X-ray absorption fine structure analysis, electron paramagnetic resonance spectroscopy, and aberration-corrected high angle annular dark field scanning transmission electron microscopy confirmed the successful synthesis of AM-CoSi with abundant Si vacancies (Siv). The as-prepared CoSi alloy catalysts exhibit an order of magnitude greater activity in the oxidation of a model reactant, benzyl alcohol (BAL) to benzyl benzoate (BBE), compared with their mono-counterparts, and provide 70% yield of BBE, the highest yield reported to date. Experimental results and density functional theory calculations suggest that the CoSi alloy structure improves the BAL conversion and that Si vacancy is the main contributor to the generation of BBE, based on which a potential reaction pathway is rationally proposed. Furthermore, the CoSi alloy maintains high stability and also exhibits high activity in the selective oxidation of various alcohols with different functional groups. This work demonstrates for the first time that semimetallic CoSi alloys can be robust catalysts for the green oxidation of various alcohols and proviedes a vast opportunity for the rational design and application of other semimetal alloy catalysts.

Synthesis of Fe3O4@CdS@CQDs ternary core–shell heterostructures as a magnetically recoverable photocatalyst for selective alcohol oxidation coupled with H2O2 production

Photocatalytic aerobic oxidation of aromatic alcohols to corresponding aldehydes coupled with producing hydrogen peroxide (H2O2) represents one of the most efficient strategies for converting solar energy into chemical energy. In this work, a magnetically recoverable photocatalyst of Fe3O4@CdS@CQDs ternary core–shell heterostructures is elaborately fabricated through the hydrothermal growth of CdS on Fe3O4 nanospheres with in-situ incorporation of carbon quantum dots (CQDs) and used for selective alcohol oxidation coupled with H2O2 production. The Fe3O4@CdS@CQDs photocatalyst possess distinct advantages of full solar spectral absorption, efficient charge separation, and high stability. The Fe3O4-nanosphere cores not only endow photocatalyst with the characteristics of magnetic recovery but also form Fe3O4@CdS Z-scheme heterojunction to prevent CdS from photocorrosion. The in-situ modified CQDs act as charge mediators to accelerate the photogenerated electron-hole separation and afford active sites to facilitate H2O2 production. As a result, the Fe3O4@CdS@CQDs photocatalyst exhibits excellent performance in selectively converting benzyl alcohol to benzaldehyde accompanied with H2O2 production. The generation rates of benzaldehyde and H2O2 reach up to 57.22 and 27.06 mmol·gCdS−1·h−1, respectively. This work highlights a rational construction of magnetic heterostructure photocatalyst and its application in the photo-redox coupling reactions.

Crystalline porous ionic salts assembled from polyoxometalates and cationic capsule for the selective photocatalytic aerobic oxidation of aromatic alcohols to aldehydes

Crystalline porous ionic salts (CPISs) represent a new type of porous materials constructed by electrostatic interaction, however, synthesis of CPISs bearing pre-designed functionality while exhibiting permanent porosity is still challenging. Herein we report the facile synthesis of a series of CPISs 1-3 built from photocatalytic-active polyoxometalate (POM) clusters and cationic Zr-based capsules, which showed open porous frameworks with BET surface area up to 33 m2/g and high activity and selectivity for photo-driven aerobic oxidation of alcohols to aldehydes. Compared with the pristine POM cluster {W10}, 1 can promote the reaction in much higher efficiency due to the concerted catalysis of preinstalled {W10} and Zr-based capsule together with open channels. This work highlights the advantage of CPISs as porous heterogeneous catalysts in organic transformation, and may shed light on the rational design of more delicate CPISs-derived functional materials.

Oil foams stabilized by POSS/organosilica particle assemblies: application for aerobic oxidation of aromatic alcohols.

A novel amphiphilic polyhedral oligomeric silsesquioxane (POSS) with surfactant-like behavior was synthesized. By combining this new POSS, used as a frother, with surface-active catalytic organosilica particles, used as a stabilizer, we designed a dual particle system able to generate foams in pure organic solvents. Tunable foamability and foam stability were achieved in a variety of organic solvents by simply adjusting the POSS concentration. As a result, the catalytic activity was drastically boosted in the aerobic oxidation of pure aromatic alcohols under 1 bar O2 pressure. Particles were conveniently recycled with high foamability and the catalytic efficiency was maintained for at least 7 consecutive runs.

Steric Effects of Mesoporous Silica Supported Bimetallic Au-Pt Catalysts on the Selective Aerobic Oxidation of Aromatic Alcohols

Three series of catalysts consisting of gold (Au), platinum (Pt), or gold-platinum bimetallic nanoparticles (NPs) with controlled sizes (Au NPs 10 ± 2 nm, Pt NPs 6 ± 2 nm) anchored on hierarchical micro-/meso-/macroporous silica were successfully developed and systematically evaluated for the selective oxidation of aromatic alcohols to their corresponding aldehydes. The catalysts were prepared by the sol-immobilization method using as-made Au NPs and/or Pt NPs colloids; the silica supports were prepared with controlled pore structures and the hierarchical porous structures of catalysts were created by controllable desilication via the alkaline solution of the metal colloids. The catalysts were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), and these results showed no synergistic effect between Au and Pt on boosting the catalytic performance, whereas they demonstrated a clear dependence of catalytic conversions and reaction rates on the structural porosity of Au-Pt bimetallic catalysts. Our findings could potentially inspire peer researchers and scientists to develop designer porous catalysts and processes in the selective organic conversions.

Ultrathin Phosphate-Modulated Co Phthalocyanine/g-C3N4 Heterojunction Photocatalysts with Single Co-N4 (II) Sites for Efficient O2 Activation.

Realization of solar‐driven aerobic organic transformation under atmospheric pressure raises the great challenge for efficiently activating O2 by tailored photocatalysts. Guided by theoretical calculation, phosphate groups are used to induce the construction of ultrathin Co phthalocyanine/g‐C3N4 heterojunctions (CoPc/P‐CN, ≈4 nm) via strengthened H‐bonding interfacial connection, achieving an unprecedented 14‐time photoactivity improvement for UV–vis aerobic 2,4‐dichlorophenol degradation compared to bulk CN by promoted activation of O2. It is validated that more •O2 − radicals are produced through the improved photoreduction of O2 by accelerated photoelectron transfer from CN to the ligand of CoPc and then to the abundant single Co–N4 (II) catalytic sites, as endowed by the matched dimension, intimate interface even at the molecular level, and high CoPc dispersion of resulted heterojunctions. Interestingly, CoPc/P‐CN also exhibits outstanding photoactivities in the aerobic oxidation of aromatic alcohols. This work showcases a feasible route to realize efficient photocatalytic O2 activation by exploiting the potential of ultrathin metal phthalocyanine (MPc) assemblies with abundant single‐atom sites. More importantly, a universal facile strategy of H‐bonding‐dominating construction of MPc‐involved heterojunctions is successfully established.

Chalcogenide photocatalysts for selective oxidation of aromatic alcohols to aldehydes using O2 and visible light: A case study of CdIn2S4, CdS and In2S3

CdIn2S4, CdS and In2S3 photocatalysts were fabricated via a facile solvothermal method using indium chloride, cadmium nitrate and thiacetamide as precursors. The physicochemical and optical properties of the as-prepared samples were characterized by a series of techniques. The photocatalytic activities of the as-prepared samples were evaluated by selective aerobic oxidation of aromatic alcohols to corresponding aldehydes under visible light illumination. Compared with pure In2S3 and CdS samples, CdIn2S4 photocatalyst shows superior photocatalytic performance for selective oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). Under the optimal conditions, the conversion and selectivity for photocatalytic selective oxidation of BA to BAD are 80.1 and 98.8% under visible light irradiation for 2 h, respectively. The excellent photocatalytic performance of CdIn2S4 photocatalyst should be ascribed to its unique structure with a favorable absorptivity, appropriate conduction band and valence band positions and longer lifetime of photogenerated charge carriers. A possible reaction mechanism for selective oxidation of BA to BAD over CdIn2S4 photocatalyst with O2 and visible light is proposed. It is hoped that the current work could offer an avenue to prepare high-performance chalcogenide photocatalysts used in the field of photocatalytic selective organic transformations.

An insight into the superior performance of a gold nanocatalyst on single wall carbon nanotubes to that on titanium dioxide and amorphous carbon for the green aerobic oxidation of aromatic alcohols

An insight into the superior performance of a gold nanocatalyst on single wall carbon nanotubes to that on titanium dioxide and amorphous carbon for the green aerobic oxidation of aromatic alcohols

An insight into the superior performance of a gold nanocatalyst on single wall carbon nanotubes to that on titanium dioxide and amorphous carbon for the green aerobic oxidation of aromatic alcohols

Gold nanocomposites based on three supports, single wall carbon nanotubes, carbon black and TiO2, were prepared using an in-situ reduction technique and characterized. They were tested for their suitability as heterogeneous catalysts in the green aerobic oxidation of 1-phenylethanol, 2-phenylethanol and benzylalcohol of industrial importance. For all reactions, the use of single wall carbon nanotubes as supports resulted in superior reaction efficiency and specificity for aldehyde to that of TiO2 and carbon black. The gold nanocatalysts can be reused over several reaction cycles with a minimal degeneration in catalytic activity. The activity of the gold nanoparticle catalyst was related to the shape and size of the gold particles and the properties of the support. The selectivity was ascribed to the functional groups on the substrate, the properties of the supports and the particle size distributions of the gold nanoparticles.

PANI/FeUiO-66 nanohybrids with enhanced visible-light promoted photocatalytic activity for the selectively aerobic oxidation of aromatic alcohols

Metal-organic frameworks (MOFs), a new class of porous crystalline materials, have attracted great interest as fascinating applications for eco-friendly photocatalysts. In this study, new hybrid MOFs, iron doped zirconium based metal-organic frameworks, FeUiO-66, were successfully synthesized by hydrothermal method firstly. Then the PANI/FeUiO-66 nanohybrids were fabricated through annealing process. The photocatalytic performances of the obtained PANI/FeUiO-66 nanohybrids were evaluated by selectively oxidation of various alcohol substrates using molecular oxygen as a benign oxidant. Boosting by synergistically multi-doped effect, the catalytic activity of the novel PANI/FeUiO-66 is remarkably higher than that of bare UiO-66 under visible light irradiation at ambient temperature. Further analyses revealed that the enhancement of photocatalytic activity originated from the two aspects. On one hand, when the Fe doped into the framework, valence fluctuation of Fe2+/Fe3+ could reduce the recombination rate of photoexcited carriers. On the other hand, based on energy band matching between FeUiO-66 and PANI, the easily formed heterostructures from PANI and FeUiO-66 can efficiently enhance the separation of photogenerated carriers. Furthermore, by virtue of unique advantage of the position of the CB and VB of FeUiO-66, alcohols could be selectively oxidized by the O2− and h+. Remarkably, it is expected that the MOF-conductive conjugated polymers nanohybrids could be used as efficient visible light driven photocatalysts for organic transformation with high selectivity under eco-friendly conditions.

Ultrafine MnO2 nanoparticles decorated on graphene oxide as a highly efficient and recyclable catalyst for aerobic oxidation of benzyl alcohol

The highly active and selective aerobic oxidation of aromatic alcohols over earth-abundant, inexpensive and recyclable catalysts is highly desirable. We fabricated herein MnO2/graphene oxide (GO) composites by a facile in-situ growth approach at room temperature and used them in selective aerobic oxidation of benzyl alcohol to benzaldehyde. TEM, XRD, FTIR, XPS and N2 adsorption/desorption analysis were employed to systematically investigate the morphology, particle size, structure and surface properties of the catalysts. The 96.8% benzyl alcohol conversion and 100% benzaldehyde selectivity over the MnO2/GO (10/100) catalyst with well dispersive ultrafine MnO2 nanoparticles (ca. 3nm) can be obtained within 3h under 383K. Simultaneously, no appreciable loss of activity and selectivity occurred after recycling use up to six times. Due to their significant low cost, excellent catalytic performance, the MnO2/GO composites have huge application prospect in organic synthesis.

Visible-light-induced aerobic photocatalytic oxidation of aromatic alcohols to aldehydes over Ni-doped NH2-MIL-125(Ti)

The Ni-doped NH2-MIL-125(Ti) catalyst was developed for the photocatalytic aerobic oxidation of aromatic alcohols upon visible light irradiation. The results show that different aromatic alcohols can be effectively transformed to their corresponding aldehydes with almost absolute selectivity using O2 as the oxidant over Ni-doped NH2-MIL-125(Ti) upon visible light irradiation. Compared with the parent catalyst NH2-MIL-125(Ti), Ni-doped NH2-MIL-125(Ti) exhibits a significantly enhanced photocatalytic activity for the selective oxidation of aromatic alcohols. Preliminary studies indicate that the doping of Ni nanoparticles into NH2-MIL-125(Ti) could improve the visible-light harvesting, charge-separation, and electron-transport of the resultant catalyst, leading to the enhanced photocatalytic activity. The current work provides some guidance in the development of MOF-based photocatalysts for organic syntheses.

ChemInform Abstract: Nanoscaled Copper Metal‐Organic Framework (MOF) Based on Carboxylate Ligands as an Efficient Heterogeneous Catalyst for Aerobic Epoxidation of Olefins and Oxidation of Benzylic and Allylic Alcohols.

ChemInformVolume 46, Issue 24 Heterocyclic Compounds ChemInform Abstract: Nanoscaled Copper Metal-Organic Framework (MOF) Based on Carboxylate Ligands as an Efficient Heterogeneous Catalyst for Aerobic Epoxidation of Olefins and Oxidation of Benzylic and Allylic Alcohols. Yue Qi, Yue Qi Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorYi Luan, Yi Luan Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorJie Yu, Jie Yu Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorXiong Peng, Xiong Peng Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorGe Wang, Ge Wang Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this author Yue Qi, Yue Qi Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorYi Luan, Yi Luan Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorJie Yu, Jie Yu Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorXiong Peng, Xiong Peng Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this authorGe Wang, Ge Wang Sch. Mater. Sci. Eng., Univ. Sci. Technol. Beijing, Beijing 100083, Peop. Rep. ChinaSearch for more papers by this author First published: 27 May 2015 https://doi.org/10.1002/chin.201524115Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume46, Issue24June, 2015 RelatedInformation

Nanoscaled copper metal-organic framework (MOF) based on carboxylate ligands as an efficient heterogeneous catalyst for aerobic epoxidation of olefins and oxidation of benzylic and allylic alcohols.

Aerobic epoxidation of olefins at a mild reaction temperature has been carried out by using nanomorphology of [Cu3(BTC)2] (BTC = 1,3,5-benzenetricarboxylate) as a high-performance catalyst through a simple synthetic strategy. An aromatic carboxylate ligand was employed to furnish a heterogeneous copper catalyst and also serves as the ligand for enhanced catalytic activities in the catalytic reaction. The utilization of a copper metal-organic framework catalyst was further extended to the aerobic oxidation of aromatic alcohols. The shape and size selectivity of the catalyst in olefin epoxidation and alcohol oxidation was investigated. Furthermore, the as-synthesized copper catalyst can be easily recovered and reused several times without leaching of active species or significant loss of activity.

Transition metal-free catalytic oxidation of aromatic alcohols with molecular oxygen in the presence of a catalytic amount of N-bromosuccinimide

A highly efficient N-bromosuccinimide (NBS)-mediated transition metal-free catalytic system has developed for the efficient aerobic oxidation of aromatic alcohols. Various aromatic alcohols are successfully oxidized to the corresponding aldehydes or ketones under mild condition. For instance, benzyl alcohol is oxidized to benzaldehyde with 99% conversion in 94.5% selectivity with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)–NaNO2–NBS system under 0.3MPa of O2 at 90°C for 2h. The effects of reaction time, catalyst amount and solvents are investigated in detail, and a possible reaction mechanism is proposed.

Binary Pd–Polyoxometalates and Isolation of a Ternary Pd–V–Polyoxomolybdate Active Species for Selective Aerobic Oxidation of Alcohols

Binary Pd-polyoxometalates [Pd(dpa)2]3 [PW12 O40]2 ⋅12 DMSO (2), [Pd(dpa)2]3 [PMo12 O40]2 ⋅12 DMSO⋅2 H2 O (3), and [Pd(dpa)(DMSO)2]2 [HPMo10 V2 O40 ]⋅4 DMSO (4) were synthesized by reaction of [Pd(dpa)(OAc)2]⋅2 H2 O (1; dpa=2,2'-dipyridylamine) with three Keggin-type polyoxometalates and fully characterized by single-crystal and powder XRD analyses, IR spectroscopy, and elemental analyses. The synthesis is facile and straightforward, and the complicated ligand-modification procedure often used in the traditional charge-transfer method can be omitted. In 2-4, Pd complexes and polyoxometalate anions are coupled through electrostatic interaction. Compound 4 is more active than the other three compounds in the selective aerobic oxidation of alcohols at ambient pressure. Interestingly, during catalytic recycling of compound 4, unprecedented ternary Pd-V-polyoxometalate [Pd(dpa)2 {VO(DMSO)5}2][PMo12 O40]2 ⋅4 DMSO (5), which was captured and characterized by single-crystal XRD, proved to be the true active species and showed high catalytic activity for the selective aerobic oxidation of aromatic alcohols (98.1-99.8 % conversion, 91.5-99.1 % selectivity). Moreover, on the basis of control experiments and EPR and UV/Vis spectra, a plausible reaction mechanism for the oxidation of alcohols catalyzed by 5 was proposed.

Triple nanocomposites of CoMn2O4, Co3O4 and reduced graphene oxide for oxidation of aromatic alcohols

A composite of reduced graphene oxide (RGO) with oxides of manganese and cobalt together was prepared by a solvothermal method. During synthesis, both the reduction of graphene oxide as well as the growth of nanorod shaped CoMn2O4 and Co3O4 occurred simultaneously having a crystallite size of ~8 nm calculated from X-ray diffraction (XRD). The as-obtained triple nanocomposite material designated as RGO–MnCoO exhibited excellent activity for the liquid phase aerobic oxidation of aromatic alcohols under base-free conditions selectively giving the corresponding aldehydes (>85%). RGO loading was varied in the range of 1–10%, among which 1% RGO–MnCoO showed maximum catalytic activity enhancement of 24% as compared to the bare mixed oxide (MnCo-MO) for the oxidation of vanillyl alcohol. HR-TEM of RGO–MnCoO revealed that it was a composite material having uniform nanotubes of ~25 nm length and 6 nm diameter with a fringe pattern showing the (103) and (004) planes and lattice spaces of 0.26 nm and 0.22 nm, respectively, for the spinel CoMn2O4. The detailed studies on the morphology, size and composition of the as-prepared RGO–MnCoO nanocomposite by XRD, XPS, N2-adsorption/desorption and O2-TPD techniques were used to understand the role of RGO in the enhancement of catalytic activity for oxidation reaction.

Palladium on graphene as efficient catalyst for solvent-free aerobic oxidation of aromatic alcohols: Role of graphene support

Palladium catalysts supported on different carbon materials, i.e. graphene, carbon nanotube and activated carbon, have been prepared by improved wet impregnation and employed in the solvent-free aerobic oxidation of aromatic alcohols using molecular oxygen as oxidant. High catalytic activity as well as high selectivity to corresponding carbonyl compounds can be obtained on Pd/graphene. Typically, an extremely high turnover frequency of 30,137mol/hmolPd is observed in the aerobic oxidation of benzyl alcohol to benzaldehyde using Pd/graphene as catalyst. Palladium catalysts on different carbon supports are fully characterized by a series of techniques, e.g. Raman, XRD, SEM, TEM, TG, XPS, FTIR spectra of benzyl alcohol adsorption and O2-TPD. Based on the catalytic and characterization results, the superior reactivity of Pd/graphene in the aerobic oxidation of aromatic alcohols is attributed to the promotion role of graphene support in the adsorption of reactant alcohol and oxygen.

ChemInform Abstract: Synthesis of Bimagnetic Ionic Liquid and Application for Selective Aerobic Oxidation of Aromatic Alcohols under Mild Conditions.

The first bimagnetic ionic liquid based on Fe and TEMPO with cooperative functionalities not only exhibited strong paramagnetic behaviour at room temperature under an applied magnetic field of 5000 Oe but also proved to be an effective catalyst for selective aerobic oxidation of aromatic alcohols under mild and clean conditions.

Synthesis of bimagnetic ionic liquid and application for selective aerobic oxidation of aromatic alcohols under mild conditions

The first bimagnetic ionic liquid based on Fe and TEMPO with cooperative functionalities not only exhibited strong paramagnetic behaviour at room temperature under an applied magnetic field of 5000 Oe but also proved to be an effective catalyst for selective aerobic oxidation of aromatic alcohols under mild and clean conditions.