- Alcohol oxidation and aldol condensation during base-catalyzed reaction of primary alcohols with 1-chloroanthraquinone
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When chloroanthraquinone is treated with primary alcohols under basic conditions, the notoriously low yields observed for substitution result in part from oxidation of the alcohol followed by aldol condensation. (C) 2000 Elsevier Science Ltd.
- Shabany,Abel,Evans,McRobbie,Gokel
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- Electron Paramagnetic Resonance, ENDOR and TRIPLE Resonance of some 9,10-Anthraquinol Radicals in Solution
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EPR, ENDOR and TRIPLE resonance spectra are recorded for 9,10-anthraquinol-1-sodium sulphonate, 9,10-anthraquinol-2-sodium sulphonate, 9,10-anthraquinol-1,5-disodium sulphonate and 9,10-anthraquinol-2,6-disodium sulphonate cation radicals.The splittings of the 9,10-anthraquinol cation radical have been assigned by deuteration.The spectra of the deuterated anthraquinol cation radicals and the assignment of hyperfine coupling constants are discussed.
- Maekelae, Reijo,Vuolle, Mikko
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- Kinetics and mechanism of anthracene oxidation with tert-butyl hydroperoxide over metal-organic frameworks Cr-MIL-101 and Cr-MIL-100
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The oxidation of anthracene (AN) with tert-butyl hydroperoxide (TBHP) over metal-organic frameworks (MOFs) Cr-MIL-101 and Cr-MIL-100 produced anthraquinone (AQ) in a nearly quantitative (>99%) yield after 1 and 4 h, respectively, at 100 °C in chlorobenzene (ClPh). At initial stages of the reaction, some amounts (a was found to be similar for MIL-101 and MIL-100 (15 kcal/mol) while pre-exponential factors were different (7·106 and 3·106 L/(mol·min), respectively). The kinetic results indicated that the AN oxidation with TBHP over both MIL-101 and MIL-100 is not controlled by diffusion. No adsorption of AN on the MOFs from ClPh solution was found at the reaction temperature. A mechanism that involves a reversible interaction between TBHP and CrIII centers within the MOF framework producing an active oxidizing species (rate-limiting step), followed by oxygen atom transfer from the peroxo species to the aromatic substrate to give primary oxygenated product(s), further oxidation of which leads to AQ, has been suggested.
- Ivanchikova,Skobelev,Kholdeeva
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- Oxidation with the H2O2-VO3--pyrazine-2-carboxylic acid reagent 2. Oxidation of alcohols and aromatic hydrocarbons
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Aromatic hydrocarbons are oxidized with hydrogen peroxide in the presence of catalytic amounts of VO3- and pyrazine-2-carboxylic acid into phenols (provided excess hydrocarbon is used) or into quinones (at high H2O2 concentrations). 2-Propanol, ethanol, cyclohexanol, and benzyl alcohol are transformed into the corresponding aldehydes and ketones under the same conditions (without a solvent or in MeCN). - Key words: oxidation, hydrogen peroxide, vanadium complexes; aromatic hydrocarbons; alcohols.
- Shul'pin, G. B.,Druzhinina, A. N.,Nizova, G. V.
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- Pulse Radiolyses of Anthraquinone and Anthraquinone-Triethylamine in Acetonitrile and Toluene at Room Temperature
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Nanosecond pulse radiolysis of anthraquinone (AQ) in several solvents has been performed at room temperature, and the following results are obtained: (1) In acetonitrile (CH3CN), the formation of triplet AQ and a free-radical anion (AQ.-) of AQ is observed.The former is produced by energy transfer from an excited neutral of CH3CN which may be produced via the geminate recombination of a radical cation and a radical anion of CH3CN in a spur, while the latter is produced by electron transfer from anionic species such as a solvated electron, a monomeric and/or dimeric radical anion of CH3CN.In CH3CN-triethylamine (TEA), both free AQ.- and triplet AQ mentioned above are also produced; however, the latter reacts with TEA, giving rise to the formation of free AQ.- (from the second triplet state of AQ) and an exciplex of the lowest triplet state of AQ with ground-state TEA.This exciplex decomposes to free AQ.- and the radical cation of TEA. (2) In toluene, only triplet AQ is produced by energy transfer from triplet toluene to AQ, and, in the presence of TEA, the formation of the triplet exciplex of AQ-TEA is observed.On a microsecond timescale, however, this exciplex changes to a contact ion pair followed by proton transfer, generating anthrasemiquinone radical and triethylamine radical in accordance with the result of photolysis.
- Nakayama, Toshihiro,Ushida, Kiminori,Hamanoue, Kumao,Washio, Masakazu,Tagawa, Seiichi,Tabata, Yoneho
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- Self-Assembled Cofacial Zinc–Porphyrin Supramolecular Nanocapsules as Tuneable 1O2 Photosensitizers
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We demonstrate the benefits of using cofacial Zn–porphyrins as structural synthons in coordination-driven self-assembled prisms to produce cage-like singlet oxygen (1O2) photosensitizers with tunable properties. In particular, we describe the photosensitizing and emission properties of palladium- and copper-based supramolecular capsules, and demonstrate that the nature of the bridging metal nodes in these discrete self-assembled prisms strongly influences 1O2 generation at the Zn–porphyrin centers. The PdII-based prism is a particularly robust photosensitizer, whereas the CuII self-assembled prism is a dormant photosensitizer that could be switched to a ON state upon disassembly of the suprastructure. Furthermore, the well-defined cavity within the prisms allowed encapsulation of pyridine-based ligands and fullerene derivatives, which led to a remarkable guest tuning of the 1O2 production.
- Colomban, Cédric,Fuertes-Espinosa, Carles,Goeb, Sébastien,Sallé, Marc,Costas, Miquel,Blancafort, Lluís,Ribas, Xavi
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- Photoproducts of carminic acid formed by a composite from Manihot dulcis waste
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Carbon-TiO2 composites were obtained from carbonised Manihot dulcis waste and TiO2 using glycerol as an additive and thermally treating the composites at 800 °C. Furthermore, carbon was obtained from manihot to study the adsorption,
- Antonio-Cisneros, Cynthia M.,Dvila-Jimnez, Martn M.,Elizalde-Gonzlez, Mara P.,Garca-Daz, Esmeralda
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- INTRODUCTION OF ONE-CARBON UNITS DURING ANTHRAQUINONE-CATALYSED PULPING OF WOOD
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Anthraquinone- and tetrahydroanthraquinone-catalysed pulping of Pinus radiata has given 10-methyl-9-anthrone (2) and derivatives (3) and (4), introduction of the carbon substituent involving carbohydrate constituents of the wood.
- Cameron, Donald W.,Samuel, Eva L.
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- Anthrone complexation with aliphatic amines in an aprotic medium
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Aromatic ketone (anthrone) complexation with aliphatic amines is studied by UV-Vis, 1H, 1H-1H COSY NMR spectroscopy. It is found that the catalytic activity of aliphatic amine is observed in the reaction of anthrone oxidation by molecular oxygen in aprotic media due to the formation of intermolecular complexes consisting of two anthrone molecules and one aliphatic amine molecule.
- Serdyuk,Abakumov,Kapitanov,Kasianczuk,Opeida
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- Novel highly stable β-cyclodextrin fullerene mixed valent Fe-metal framework for quick Fenton degradation of alizarin
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β-Cyclodextrin (β-CD) supported magnetic nanoscaled fullerene/Fe3O4 (CDFMNPs) and fullerene/Fe3O4 (FMNPs) composites were prepared and characterized. These composites can be utilized as heterogeneous catalysts for the Fenton oxidation reaction to degrade alizarin in aqueous solutions. The saturation magnetization (Ms) value of quasi-spherical CDFMNPs was found to be 13.16 emu g-1 and their diameter was in the range of 25-30 nm. The catalytic activities of the prepared materials were tested with varying conditions of pH, amount used and the concentration of H2O2 for degradation of alizarin at room temperature. The exceptionally high degradation efficiency of CDFMNPs was observed for alizarin at pH 3 with 2.0 g L-1 catalyst and 25 mM of H2O2. The increased oxidative degradation efficiency is attributed mainly to the formation of active hydroxyl radicals (OH) on the surface of the catalyst, which are generated by the active decomposition of H2O2 by the solid heterogeneous catalyst and the promoting effect of β-CD. CDFMNPs can be magnetically separated and the catalyst was found to be reusable and stable for five successive runs with no significant loss of catalytic activity. In the magnetic environment of Fe3O4 nanoparticles, fullerene has a crucial role to enhance the activity by increasing the stability with nominal iron leaching. Based on mass analysis of alizarin degradation, the formation of aliphatic acids and monocyclic compounds through phthalic anhydride and di-methyl phthalate established the proposed degradation path.
- Gogoi, Aniruddha,Navgire, Madhukar,Sarma, Kanak Chandra,Gogoi, Parikshit
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- The influence of the structure of aliphatic amine on its catalytic activity in the oxidation of anthrone in dimethyl sulfoxide
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The catalytic activity of several aliphatic amines in the liquid-phase oxidation of anthrone by molecular oxygen in dimethyl sulfoxide was studied. The kinetic data obtained were compared with the results of quantum-chemical calculations. The catalytic activity of aliphatic amines in the reaction under consideration was directly proportional to an increase in the absolute value of the heat of formation of the corresponding ammonium cation.
- Serdyuk,Kasyanchuk,Opeida,Tolkunov
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- Quinaldinium fluorochromate and quinaldinium dichromate: Two new and efficient reagents for the oxidation of alcohols
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Two new mild oxidizing agents, quinaldinium fluorochromate and quinaldinium dichromate, were prepared and characterized. These reagents are suitable to oxidize various primary and secondary alcohols to the corresponding carbonyl compounds and anthracene to antraquinone in good yields. Springer-Verlag 2004.
- Degirmenbasi, Nebahat,Oezguen, Beytiye
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- Matrix Isolation of 3,4-Benzocyclodeca-3,7,9-triene-1,5-diyne
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3,4-Benzocyclodeca-3,7,9-triene-1,5-diyne (3) has been synthesized from two different precursors and characterized by means of matrix-isolation spectroscopy. Energies, structures and IR spectra of the product, the intermediate 9,10-didehydroanthracene (4), and of the transition state of the Bergman cyclization 3 → 4 have been calculated at the B3LYP/6-31G * level of theory.
- Koetting, Carsten,Sander, Wolfram,Kammermeier, Stefan,Herges, Rainer
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- Production of ROS by photosensitized anthracene under sunlight and UV-R at ambient environmental intensities
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The aim of this study was to analyze the photostability and phototoxicity mechanism of anthracene (ANT) in a human skin epidermal cell line (HaCaT) at ambient environmental intensities of sunlight/UV-R (UV-A and UV-B). Photomodification of ANT under sunlight/UV-R exposure produced two photoproducts, anthrone and 9,10 anthracenedione. Generation of 1O2, O2?- and ?OH was measured under UV-R/sunlight exposure. Involvement of reactive oxygen species (ROS) was further substantiated by their quenching with free radical quenchers. Photodegradation of 2-deoxyguanosine and linoleic acid peroxidation showed that ROS were mainly responsible for ANT phototoxicity. ANT generates significant amount of intracellular ROS in cell line. Maximum cell viability (85%) was reduced under sunlight exposure (30 min). Results of MTT assay accord NRU assay. ANT (0.01 μg mL-1) induced cell-cycle arrest at G1 phase. RT-PCR demonstrated constitutive inducible mRNA expression of CYP 1A1 and 1B1 genes. Photosensitive ANT upregulates CYP 1A1 (2.2-folds) and 1B1 (4.1-folds) genes. Thus, the study suggests that ROS and DNA damage were mainly responsible for ANT phototoxicity. ANT exposure may be deleterious to human health at ambient environmental intensities reaching the earth's surface through sunlight. Mechanism of anthracene was assessed on HaCaT cell line at ambient environmental intensities of sunlight/UV-R. Anthracene under sunlight/UV-R exposure produced anthrone and 9,10 anthracenedione. Generation of 1O2, O2?-, and ?OH was measured under UV-R/sunlight exposure. Photodegradation of 2-deoxyguanosine and linoleic acid peroxidation showed that ROS were mainly responsible for phototoxicity. Anthracene generates intracellular ROS in cell line. Maximum phototoxicity was observed under sunlight. Anthracene induced cell cycle arrest at G1 phase. RT-PCR study shows upregulation of CYP 1A1 and 1B1 genes. Thus, the study suggests that ROS and DNA damage were mainly responsible for anthracene phototoxicity.
- Mujtaba, Syed Faiz,Dwivedi, Ashish,Mudiam, Mohana Krishna Reddy,Ali, Daoud,Yadav, Neera,Ray, Ratan Singh
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- Thermochromism at room temperature in overcrowded bistricyclic aromatic enes: Closely populated twisted and folded conformations
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The overcrowded thermochromic bistricyclic aromatic enes (BAEs) 10-(9′H-fluoren-9′-ylidene)-9(10H)-anthracenone (6), 10-(11′H-benzo[b]fluoren-11′-ylidene)-9(10H)-anthracenone (7), and 10-(1′,8′-diaza-9′H-fluoren-9′-ylidene)-9(10H) -anthracenone (8) were synthesized by applying Barton's two-fold extrusion diazo-thione coupling method and their crystal and molecular structures were determined. BAEs 6-8 exhibit thermochromic behavior at room temperature due to the equilibrium between the yellow anti-folded conformations and the thermochromic purple, blue, or red twisted conformations. The NMR experiments demonstrate a fast interconversion of the twisted and the anti-folded conformers of 6-8 in solution. BAE 7 readily undergoes E,Z-topomerization at room temperature with the coalescence point at 297 K and the relatively low energy barrier of ΔGc?(t⊥) = 65.5 kJ/mol. B3LYP/6-311++G(d,p) calculations predict anti-folded a-6 and a-7 to be less stable than twisted t-6 and t-7 by 0.8 and 1.3 kJ/mol, respectively, whereas a-8 is more stable than t-8 by 10.7 kJ/mol. DFT calculations of 6-8, 9-(9′H-fluoren-9′-ylidene)-9H-fluorene (1), [10′-oxo- 9′(10′H)-anthracenylidene]-9(10H)-anthracenone (2) and their 1,8-diaza-substituted derivatives show that substitution in the fluorenylidene unit destabilizes the twisted conformations by 11-22 kJ/mol, while introduction of nitrogen atoms at the 1 and 8 positions of anthracenylidene unit destabilizes the anti-folded conformations by 14-18 kJ/mol. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Levy, Amalia,Pogodin, Sergey,Cohen, Shmuel,Agranat, Israel
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- Self-immolative polymersomes for high-efficiency triggered release and programmed enzymatic reactions
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Stimuli-triggered disassembly of block copolymer vesicles or polymersomes has been conventionally achieved via solubility switching of the bilayer-forming block, requiring cooperative changes of most of the repeating units. Herein we report an alternative
- Liu, Guhuan,Wang, Xiaorui,Hu, Jinming,Zhang, Guoying,Liu, Shiyong
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- Quinaldinium Chlorochromate Supported on Alumina: A New and Efficient Reagent for the Oxidation of Alcohols
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The new, mild chromium(VI) oxidizing agent, quinaldinium chlorochromate supported on neutral alumina, was prepared as a stable yellow solid. The reagent is suitable to oxidize various primary and secondary alcohols to the corresponding carbonyl compounds and anthracene to anthraquinone in good yields.
- Degirmenbasi, Nebahat,Oezguen, Beytiye
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- Degradable Holey Palladium Nanosheets with Highly Active 1D Nanoholes for Synergetic Phototherapy of Hypoxic Tumors
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Pd nanosheets (Pd NSs) have attracted extensive attention due to their promising application in photothermal therapy. However, their photodynamic properties have rarely been reported. Herein, holey Pd NSs (H-Pd NSs) with intrinsic photodynamic and hypoxia-resistant capacities are fabricated for the first time using an anisotropic oxidative etching strategy, which introduces one-dimensional nanoholes with active (100) facets on the hole walls. Gradual degradation of H-Pd NSs is observed in simulated physiological media due to the oxidative etching. In vitro and in vivo studies indicate that the single-component H-Pd NSs can act as a photothermal/photodynamic agent for imaging-guided hypoxic tumor therapy, with a high tumor inhibition rate of 99.7%. This work provides ideas for introducing active facets in metallic pore walls, broadening the application of Pd NSs and the design of biodegradable noble metal nanotheranostic agents for cancer therapy.
- Gu, Kai,Huang, Zhijun,Li, Huawei,Li, Shanshan,Liu, Huiyu,Shi, Xinghua,Wang, Hui,Xu, Bolong
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- Kinetics of amine catalysed oxidation of anthrone by oxygen in aprotic solvents
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Catalytic activity for the series of aliphatic and aromatic amines in liquid-phase oxidation of anthrone with molecular oxygen was studied gas-volumetrically and spectroscopically. It was shown that the studied amines are arranged in the following order of decreasing catalytic activity: NH 3 > RNH2 > R1R2NH > R 1R2R3N > ArNR2. A kinetic scheme for the process is proposed. Pleiades Publishing, Ltd., 2010.
- Serdyuk,Kasianchuk,Opeida
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- Photochemical Expulsion of Iodide from the 1-Iodoanthraquinone Radical Anion
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The electochemical reduction of 1-iodoanthraquinone in acetonitrile solvent, in the presence of tetrabutylammonium perchlorate , at electrodes irradiated with light corresponding to an absorption band of the 1-iodoanthraquinone radical anion, is shown to produce the radical anion of anthraquinone via a mixed ECE/DISP 1 mechanism.The rate of explusion of the iodide anion is quantified and excitation at 565 nm is approximately 7.5 times faster in this respect than at 417 nm.Novel in situ spectrofluorimetric electrochemical experiments reveal emmission from two different excited states, and the causes of the contrasting rates of iodide loss are discussed.
- Compton, Richard G.,Fisher, Adrian C.,Wellington, R. Geoffrey,Bethell, Donald,Lederer, Pavel
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- Supramolecular Self-Assembly of Histidine-Capped-Dialkoxy-Anthracene: A Visible-Light-Triggered Platform for Facile siRNA Delivery
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Supramolecular self-assembly of histidine-capped-dialkoxy-anthracene (HDA) results in the formation of light-responsive nanostructures. Single-crystal X-ray diffraction analysis of HDA shows two types of hydrogen bonding. The first hydrogen bond is established between the imidazole moieties while the second involves the oxygen atom of one amide group and the hydrogen atom of a second amide group. When protonated in acidic aqueous media, HDA successfully complexes siRNA yielding spherical nanostructures. This biocompatible platform controllably delivers siRNA with high efficacy upon visible-light irradiation leading up to 90 % of gene silencing in live cells.
- Patil, Sachin P.,Moosa, Basem A.,Alsaiari, Shahad,Alamoudi, Kholod,Alshamsan, Aws,AlMalik, Abdulaziz,Adil, Karim,Eddaoudi, Mohamed,Khashab, Niveen M.
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- Anthracene-based fluorescence turn-on chemodosimeter for the recognition of persulfate anion
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The anthracene thiosemicarbazone (ATSC) fluorescence 'turn-on' chemodosimeter for the detection of the persulfate anion (S2O82-) in 90% DMSO has been developed. ATSC is simple and exhibits high selectivity toward S2O82- anion in the presence of large interferences from other anions or cations. A fluorescence change from blue to green visualized under the UV light makes it possible to detect the persulfate anion with naked-eye. A mechanism underlying the molecular recognition has been explained from the 1H-NMR and single crystal X-ray structure experiments.
- Badekar, Pooja S.,Kumbhar, Anupa A.
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- Solid-state photolysis of anthracene-linked ammonium salts: The search for topochemical anthracene photodimerizations
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The reaction of 9-N,N-dimethylaminomethylanthracene 1 with aromatic carboxylic acids gave crystalline salts (2a, 2b, 3a and 3b), which were irradiated in the solid state. Whereas salt 3a was selectively transformed to the dimer 4a, the other salts were ph
- Ihmels, Heiko,Leusser, Dirk,Pfeiffer, Matthias,Stalke, Dietmar
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- Kinetics of Oxidation of Anthracene by Use of Copper(II) Chloro Complexes in a Mixture of Acetic Acid and Water
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The kinetics of initial rates of consumption of substrate in the oxidation of anthracene (AN) at 90 deg C by use of copper(II) chloro complexes in a mixture of acetic acid and water were studied, and the relationship between initial rates of consumption of substrate and initial rates of oxygen absorption was investigated.The following results were obtained.The rates of disappearance of anthracene and oxygen are approximately equal: -d/dt proportional to 1initial1/2-0initial1-0.
- Koshitani, Jinya,Kado, Toshio,Ueno, Yoshio,Yoshida, Takatoshi
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- Anthryl-1,2,4-oxadiazole-substituted calix[4]arenes as highly selective fluorescent chemodosimeters for Fe3+
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Fluorescent chemosensors 1 and 2, with 1,2,4-oxadiazoles as the binding ligands and anthracene as the fluorophore, were synthesized through sequential 1,3-dipolar cycloaddition reactions of 25,27-dioxyacetonitrilecalix[4]arenes 8 and 11. The fluorescence
- Chen, Ying-Jung,Yang, Shun-Chieh,Tsai, Chia-Chen,Chang, Kai-Chi,Chuang, Wen-Han,Chu, Wei-Lun,Kovalev, Vladimir,Chung, Wen-Sheng
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- Surface reactivities of polynuclear aromatic adsorbates on alumina and silica particles using infrared photoacoustic spectroscopy
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Infrared photoacoustic spectra were obtained from organic films on inorganic particulate adsorbents. Under favorable conditions, including strong adsorption bands and high surface area silica and alumina substrates, the detection sensitivity of photoacoustic spectroscopy is estimated to be 0. 2 monolayers of an adsorbed organic compound. Because of the molecular information provided by IR spectroscopy, reactions of adsorbed organic compounds may be examined in situ. Examples shown involve photochemical reactions of sorbed polynuclear aromatic compounds that are potentially important in the atmospheric chemistry of combustion generated aerosols.
- Saucy,Cabaniss,Linton
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- Photolysis of an Amphiphilic Assembly by Calixarene-Induced Aggregation
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Photosensitizers generally show great tendency for self-aggregation in aqueous media, leading to quenched fluorescence and lower photosensitizing ability. Herein, we report that amphiphilic anthracene is highly photoreactive after aggregation induced by p-sulfonatocalix[4]arene in water. The formation of a host-guest supramolecular assembly and the photolysis of the anthryl core are identified by UV-vis and NMR spectroscopy, dynamic light scattering, and transmission electron microscopy. Additionally, the assembly exhibited efficient photolysis with visible light in the presence of exogenous photosensitizers. This approach could be extended to various photoresponsive self-assemblies and applications in phototherapy and the design of photodegradable materials. (Chemical Equation Presented)
- Wang, Yi-Xuan,Zhang, Ying-Ming,Liu, Yu
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- Photoelectrochemical Electron Spin Resonance
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The reduction of 1-bromoanthraquinone in acetonitrile solvent in the presence of tetrabutylammonium perchlorate, at irradiated (565 nm) gold electrodes is shown to produce the radical anion of anthraquinone.A combination of photoelectrochemical hydrodynam
- Compton, Richard G.,Coles, Barry A.,Pilkington, Matthew B.,Bethell, Donald
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- The[4 + 2] cycloaddition of anthracene with C60F18; anthracene goes ring walking
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From the[4 + 2] cycloaddition of anthracene at the curved face of C60F18 we have isolated two main isomers of Cs and C1 symmetry (isomers1 and 2, respectively) in ca. 3 : 2 relative yields; isomer 2 contained tr
- Avent,Boltalina,Street,Taylor,Wei
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- Reactivity of 9-anthracenecarboxylate in the presence of Mn(II) and Mn(III) ions: Biomimetic aerobic oxidative decarboxylation catalysed by a manganese(III) 2,2′-bipyridine complex
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The stability of the 9-anthracenecarboxylate (AnthCO2–) in the presence of manganese ions and 2,2′-bipyridine (bpy) was explored. Two Mn(II) species were isolated: a one-dimensional system [Mn(bpy)(AnthCO2)2]n (1) and a dinuclear [{Mn(bpy)(AnthCO2)}2(μ-OH2)(μ-AnthCO2)2] compound (2), which was characterized by X-ray diffraction. Compound 2 can be obtained by hydrolysis of 1. These compounds present a specific electron paramagnetic resonance (EPR) signature and weak antiferromagnetic coupling, which is slightly stronger for the dinuclear complex (?4.8 cm?1) than for the chain (?1.3 cm?1). In the presence of Mn(III) ions AnthCO2– is not stable for long time. From the Mn(III) solution obtained by a comproportionation reaction between Mn(II) and Mn(VII) salts, first, a tetranuclear [Mn4(μ-AnthCO2)6(μ-O)2(bpy)2(ClO4)2] compound was isolated, showing the antiferromagnetic properties typical of a butterfly [Mn4O2]8+ core (J1 = ?41.0 cm?1, J2 = ?8.4 cm?1, J3 = ?10.6 cm?1 and DMn = ?3.7 cm?1). After that, the solution became yellow due to the reduction of the Mn(III) complex to a Mn(II) complex, and the decarboxylation and oxidation of the AnthCO2– ligand. This oxidation can lead to different compounds, depending on the reaction conditions (temperature and amount of O2): an ester, derived from the AnthCO2– and the intermediate 10-hydroxyanthrone, and the 9,10-anthraquinone.
- Albela, Belén,Bonneviot, Laurent,Corbella, Montserrat,Font-Bardia, Mercè,Garcia-Cirera, Beltzane,Turquet, Fran?ois-Xavier
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- Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
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Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
- Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
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supporting information
(2021/12/21)
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- Synthesis, structural elucidation, and catalytic activity of bimetallic rhenium-tin complexes containing Schiff base ligand
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Novel bimetallic systems with Re and Sn metals, containing Schiff base linker were designed and explored for their cooperative effect in the catalysis. ReSn bimetallic complexes were prepared by adopting a two-step synthesis procedure, which includes cova
- Kaur, Manpreet,Kapila, Akanksha,Yempally, Veeranna,Kaur, Harminder
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- Access to Diarylmethanols by Wittig Rearrangement of ortho-, meta-, and para-Benzyloxy- N-Butylbenzamides
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The N-butyl amide group, CONHBu, has been found to be an effective promoter of the [1,2]-Wittig rearrangement of aryl benzyl ethers and thus allow the two-step synthesis of isomerically pure substituted diarylmethanols starting from simple hydroxybenzoic acid derivatives. The method is compatible with a wide range of functional groups including methyl, methoxy, and fluoro, although not with nitro and, unexpectedly, is applicable to meta as well as ortho and para isomeric series.
- Aitken, R. Alan,Harper, Andrew D.,Inwood, Ryan A.,Slawin, Alexandra M. Z.
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supporting information
p. 4692 - 4701
(2022/04/07)
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- Cu2O-CuO/Chitosan Composites as Heterogeneous Catalysts for Benzylic C?H Oxidation at Room Temperature
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Recently, in catalysis, chitosan has been exploited as a macrochelating ligand for metal active species due to the presence of various functional groups in its structure. Moreover, copper-based catalysts are classified as one of the most environmentally friendly catalytic systems and their use for the oxidation of alkylarene has not been established much. Therefore, in this work, the hydrothermal synthesis of copper oxide-chitosan composites as heterogeneous catalysts for the benzylic C?H oxidation of alkylarene was investigated. Characterization results reveal mixed phases of CuO and Cu2O, inferring the ability of chitosan to act as a reducing sugar under the hydrothermal condition. The pre-existing interaction between copper species and chitosan as well as the co-existence of the Cu2O and CuO structures give rise to the efficient performance of the catalysts. The synthesized composites exhibit high activity for the oxidation of fluorene to 9-fluorenone at room temperature and small catalyst loading (1 mol % of Cu, >90 % conversion and 100 % selectivity). Superior TOF was observed, and a good scope of substrates can be converted to corresponding ketones in 48–97 % yields with these copper oxide-chitosan catalysts. In addition, the catalysts can be used for up to nine cycles without significant decrease of the activity.
- Kanarat, Jurin,Bunchuay, Thanthapatra,Klysubun, Wantana,Tantirungrotechai, Jonggol
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p. 4833 - 4840
(2021/10/07)
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- Oxidative Dearomatization of Phenols and Polycyclic Aromatics with Hydrogen Peroxide Triggered by Heterogeneous Sulfonic Acids
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We report herein a method for the oxidative dearomatization of phenols and bare polycyclic arenes into the corresponding quinoid derivatives using hydrogen peroxide. The reaction is catalyzed by sulfonic acids and best results were achieved using heterogenized species. The best results using phenols were achieved using a hybrid material, namely a perfluorinated polymer functionalized with sulfonic acid groups supported on silica. The dearomatization of polycyclic aromatic hydrocarbons performed better using the polymeric acid catalyst. These methods operate under mild conditions, using mild and benign oxidants and thus minimizing the formation of waste.
- Pancrazzi, Francesco,Maestri, Giovanni,Maggi, Raimondo,Viscardi, Rosanna
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supporting information
p. 5407 - 5414
(2021/10/25)
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- Heteroarylation of Ethers, Amides, and Alcohols with Light and O2
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An efficient protocol for the Cα-H heteroarylation of ethers, amides, and alcohols using air and light under mild conditions is described. The reaction is applicable to a wide spectrum of functional groups. The generation of C-radicals via photoinduced aerobic oxidation of ethers, amides, and alcohols is the key feature of the process. Control experiments suggest a radical pathway for the reaction.
- Bhakat, Manotosh,Biswas, Promita,Dey, Jayanta,Guin, Joyram
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supporting information
p. 6886 - 6890
(2021/09/14)
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- Combining Structural with Functional Model Properties in Iron Synthetic Analogue Complexes for the Active Site in Rabbit Lipoxygenase
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Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O-H and C-H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal·mol-1. Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.
- Bonck, Thorsten,De Waal Malefijt, Matina Elo?se,Dobbelaar, Emiel,Kelm, Harald,Klein, Johannes E. M. N.,Krüger, Hans-J?rg,Rauber, Christian,Schmitz, Markus
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supporting information
p. 13145 - 13155
(2021/09/03)
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- Selective Electrochemical Oxygenation of Alkylarenes to Carbonyls
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An efficient electrochemical method for benzylic C(sp3)-H bond oxidation has been developed. A variety of methylarenes, methylheteroarenes, and benzylic (hetero)methylenes could be converted into the desired aryl aldehydes and aryl ketones in moderate to excellent yields in an undivided cell, using O2 as the oxygen source and lutidinium perchlorate as an electrolyte. On the basis of cyclic voltammetry studies, 18O labeling experiments, and radical trapping experiments, a possible single-electron transfer mechanism has been proposed for the electrooxidation reaction.
- Li, Xue,Bai, Fang,Liu, Chaogan,Ma, Xiaowei,Gu, Chengzhi,Dai, Bin
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supporting information
p. 7445 - 7449
(2021/10/02)
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- C-H Activation by RuCo3O4Oxo Cubanes: Effects of Oxyl Radical Character and Metal-Metal Cooperativity
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High-valent multimetallic-oxo/oxyl species have been implicated as intermediates in oxidative catalysis involving proton-coupled electron transfer (PCET) reactions, but the reactive nature of these oxo species has hindered the development of an in-depth understanding of their mechanisms and multimetallic character. The mechanism of C-H oxidation by previously reported RuCo3O4 cubane complexes bearing a terminal RuV-oxo ligand, with significant oxyl radical character, was investigated. The rate-determining step involves H atom abstraction (HAA) from an organic substrate to generate a Ru-OH species and a carbon-centered radical. Radical intermediates are subsequently trapped by another equivalent of the terminal oxo to afford isolable radical-trapped cubane complexes. Density functional theory (DFT) reveals a barrierless radical combination step that is more favorable than an oxygen-rebound mechanism by 12.3 kcal mol-1. This HAA reactivity to generate organic products is influenced by steric congestion and the C-H bond dissociation energy of the substrate. Tuning the electronic properties of the cubane (i.e., spin density localized on terminal oxo, basicity, and redox potential) by varying the donor ability of ligands at the Co sites modulates C-H activations by the RuV-oxo fragment and enables construction of structure-activity relationships. These results reveal a mechanistic pathway for C-H activation by high-valent metal-oxo species with oxyl radical character and provide insights into cooperative effects of multimetallic centers in tuning PCET reactivity.
- Amtawong, Jaruwan,Balcells, David,Handford, Rex C.,Skjelstad, Bastian Bjerkem,Suslick, Benjamin A.,Tilley, T. Don
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supporting information
p. 12108 - 12119
(2021/08/20)
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- g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
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g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
- Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
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p. 2292 - 2298
(2021/04/12)
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- Insight into the chemoselective aromatic: Vs. side-chain hydroxylation of alkylaromatics with H2O2catalyzed by a non-heme imine-based iron complex
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The oxidation of a series of alkylaromatic compounds with H2O2 catalyzed by an imine-based non-heme iron complex prepared in situ by reaction of 2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2?:?2?:?1 ratio leads to a marked chemoselectivity for aromatic ring hydroxylation over side-chain oxidation. This selectivity is herein investigated in detail. Side-chain/ring oxygenated product ratio was found to increase upon decreasing the bond dissociation energy (BDE) of the benzylic C-H bond in line with expectation. Evidence for competitive reactions leading either to aromatic hydroxylation via electrophilic aromatic substitution or side-chain oxidation via benzylic hydrogen atom abstraction, promoted by a metal-based oxidant, has been provided by kinetic isotope effect analysis. This journal is
- Ticconi, Barbara,Capocasa, Giorgio,Cerrato, Andrea,Di Stefano, Stefano,Lapi, Andrea,Marincioni, Beatrice,Olivo, Giorgio,Lanzalunga, Osvaldo
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p. 171 - 178
(2021/01/28)
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- Ligand-Constraint-Induced Peroxide Activation for Electrophilic Reactivity
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μ-1,2-peroxo-bridged diiron(III) intermediates P are proposed as reactive intermediates in various biological oxidation reactions. In sMMO, P acts as an electrophile, and performs hydrogen atom and oxygen atom transfers to electron-rich substrates. In cyanobacterial ADO, however, P is postulated to react by nucleophilic attack on electrophilic carbon atoms. In biomimetic studies, the ability of μ-1,2-peroxo-bridged dimetal complexes of Fe, Co, Ni and Cu to act as nucleophiles that effect deformylation of aldehydes is documented. By performing reactivity and theoretical studies on an end-on μ-1,2-peroxodicobalt(III) complex 1 involving a non-heme ligand system, L1, supported on a Sn6O6 stannoxane core, we now show that a peroxo-bridged dimetal complex can also be a reactive electrophile. The observed electrophilic chemistry, which is induced by the constraints provided by the Sn6O6 core, represents a new domain for metal?peroxide reactivity.
- Ansari, Mursaleem,Chandra, Anirban,Kundu, Subrata,Monte-Pérez, Inés,Rajaraman, Gopalan,Ray, Kallol
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supporting information
p. 14954 - 14959
(2021/06/01)
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- Investigating reactivity and electronic structure of copper(II)-polypyridyl complexes and hydrogen peroxide
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This work presents a detailed study of the reactivity of three mononuclear CuII complexes supported by derivatives of the tetradentate ligand N,N'-bis(2-pyridylmethyl)-1,2-ethylenediamine (bispicen). The CuII complexes are capable of performing C[sbnd]H bond activation in the presence of NEt3 and H2O2 through what has been proposed computationally to be a [CuO]+ intermediate. A wavefunction-based quantum chemical investigation into the electronic structure of the proposed [CuO]+ intermediate reveals a triplet ground state predominantly consistent with an S = ? CuII center ferromagnetically coupled to an oxyl radical, though contributions from the corresponding biradicaloid CuI-oxene resonance structure may be nontrivial. Furthermore, correlation of the electronic structure of the proposed intermediate with analogous high-valent metal-oxo species capable of olefin epoxidation suggests that the CuII complexes might be also capable of olefin epoxidation in the presence of NEt3 and H2O2. To test this hypothesis experimentally, the CuII complexes are treated with NEt3 and H2O2 in the presence of alkene substrates, resulting in the formation of epoxides.
- Khazanov, Thomas M.,Botcha, Niharika Krishna,Yergeshbayeva, Sandugash,Shatruk, Michael,Mukherjee, Anusree
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- Formation of naphthoquinones and anthraquinones by carbonyl-hydroquinone/benzoquinone reactions: A potential route for the origin of 9,10-anthraquinone in tea
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The reaction of 2-alkenals (crotonaldehyde and 2-pentenal) with hydroquinones (hydroquinone and tert-butylhydroquinone) and benzoquinones (benzoquinone, methylbenzoquinone, and methoxybenzoquinone) was studied as a potential route for the endogenous formation of naphthoquinones and anthraquinones in foods. Polycyclic quinones were produced at a low water activity, within a wide pH range, and in the presence of air. 9,10-Anthraquinone formation had an activation energy of 46.1 ± 0.1 kJ·mol?1, and a reaction pathway for the formation of the different naphthoquinones and anthraquinones is proposed. These reactions also took place in tea, therefore suggesting that the common tea pollutant 9,10-anthraquinone is also a process-induced contaminant. In fact, when four commercial teas (from a total of eight studied teas) were heated at 60 °C for 72 h, they significantly (p 0.05) increased the amount of this toxicant. Reduction of 9,10-anthraquinone formation in teas is suggested to be carried out by reducing/scavenging its precursors.
- Zamora, Rosario,Hidalgo, Francisco J.
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- Nitrosoarene-Catalyzed HFIP-Assisted Transformation of Arylmethyl Halides to Aromatic Carbonyls under Aerobic Conditions
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A rare metal-free nucleophilic nitrosoarene catalysis accompanied by highly hydrogen-bond-donor (HBD) solvent, 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), organocatalytically converts arylmethyl halides to aromatic carbonyls. This protocol offers an effective means to access a diverse array of aromatic carbonyls with good chemoselectivity under mild reaction conditions. The activation of arylmethyl halides by HFIP to generate stable carbocation and autoxidation of in situ generated hydroxylamine to nitrosoarene in the presence of atmospheric O2 are the keys to success.
- Pradhan, Suman,Sharma, Vishali,Chatterjee, Indranil
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supporting information
p. 6148 - 6152
(2021/08/03)
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- Synthetic Studies of the Rubellin Natural Products: Development of a Stereoselective Strategy and Total Synthesis of (+)-Rubellin C
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This manuscript describes our studies of the class of natural products known as the rubellins, culminating in the total synthesis of (+)-rubellin C. These anthraquinone-based natural products contain a variety of stereochemical and architectural motifs, including a 6-5-6-fused ring system, 5 stereogenic centers, and a central quaternary center. Herein, we report our development of a strategy to target the stereochemically dense core and anthraquinone nucleus, including approaches such as a bifunctional allylboron and vinyl triflate reagent, an anthraquinone benzylic metalation strategy, and a late-stage anthraquinone introduction strategy. Our studies culminate in a successful route to highly functionalized anthraquinone-based natural product scaffolds and a stereoselective total synthesis of (+)-rubellin C. These strategies and outcomes will aid in synthetic planning toward anthraquinone-based natural products of high interest.
- Gartman, Jackson A.,Tambar, Uttam K.
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p. 11237 - 11262
(2021/08/16)
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- Oxidative aromatization of 4,7-dihydro-6-nitroazolo[1,5-a] pyrimidines: Synthetic possibilities and limitations, mechanism of destruction, and the theoretical and experimental substantiation
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The reaction tolerance of the multicomponent process between 3-aminoazoles, 1-morpholino2-nitroalkenes, and aldehydes was studied. The main patterns of this reaction have been established. Conditions for the oxidation of 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines were selected. Previous claims that the 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines could not be aromatised have now been refuted. Compounds with an electron-donor substituent at position seven undergo decomposition during oxidation. The phenomenon was explained based on experimental data, electro-chemical experiment, and quantum-chemical calculation. The mechanism of oxidative degradation has been proposed.
- Balyakin, Ilya A.,Chupakhin, Oleg N.,Lyapustin, Daniil N.,Rusinov, Vladimir L.,Shchepochkin, Alexander V.,Ulomsky, Evgeny N.
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- Cathodic electroorganic reaction on silicon oxide dielectric electrode
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The faradaic reaction at the insulator is counterintuitive. For this reason, electroorganic reactions at the dielectric layer have been scarcely investigated despite their interesting aspects and opportunities. In particular, the cathodic reaction at a silicon oxide surface under a negative potential bias remains unexplored. In this study, we utilize defective 200-nm-thick n+-Si/SiO2 as a dielectric electrode for electrolysis in an H-type divided cell to demonstrate the cathodic electroorganic reaction of anthracene and its derivatives. Intriguingly, the oxidized products are generated at the cathode. The experiments under various conditions provide consistent evidence supporting that the electrochemically generated hydrogen species, supposedly the hydrogen atom, is responsible for this phenomenon. The electrogenerated hydrogen species at the dielectric layer suggests a synthetic strategy for organic molecules.
- Shin, Samuel J.,Park, Sangmee,Lee, Jin-Young,Lee, Jae Gyeong,Yun, Jeongse,Hwang, Dae-Woong,Chung, Taek Dong
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p. 32939 - 32946
(2021/02/05)
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- A metal-free heterogeneous photocatalyst for the selective oxidative cleavage of CC bonds in aryl olefins: via harvesting direct solar energy
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Selective cleavage of CC bonds is highly important for the synthesis of carbonyl containing fine chemicals and pharmaceuticals. Novel methodologies such as ozonolysis reactions, Lemieux-Johnson oxidation reaction etc. already exist. Parallel to these, catalytic methods using homogeneous catalysts also have been discovered. Considering the various advantages of heterogeneous catalysts such as recyclability and stability, couple of transition metal-based heterogeneous catalysts have been applied for this reaction. However, the pharmaceutical industries prefer to use metal-free catalysts (especially transition metal-free) to avoid further leaching in the final products. This is for sure a big challenge to an organic chemist and to the pharmaceutical industries. To make this feasible, a mild and efficient protocol has been developed using polymeric carbon nitrides (PCN) as metal-free heterogeneous photocatalysts to convert various olefins into the corresponding carbonyls. Later, this catalyst has been applied in the gram scale synthesis of pharmaceutical drugs using direct solar energy. Detailed mechanistic studies revealed the actual role of oxygen, the catalyst, and the light source.
- Das, Shoubhik,Hatami, Nareh,Jooss, Christian,Lange, Niklas Simon,Ronge, Emanuel,Schilling, Waldemar,Zhang, Yu
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supporting information
p. 4516 - 4522
(2020/08/10)
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- Highly selective electrocatalytic oxidation of benzyl C-H using water as safe and sustainable oxygen source
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The selective oxidation of C-H bond is critical for feedstock manufacturing in chemical industry. Current strategies typically involve the use of oxygen or peroxide as the oxidation reagent under high temperature, which sets severe challenges in production sustainability and industrial safety. Herein, we demonstrate an environmental-friendly and safe electrocatalytic strategy for the selective oxidation of benzyl group to ketones at ambient conditions, while using water as the sole oxygen source. Water addition reduces the onset potential of anodic C-H oxidation, and produces 1-tetralone with satisfying conversion and excellent ketone to alcohol ratio. Layered MnO2 catalysts (with rich oxygen vacancies) further adjust the water affinity and facilitate the oxidation, leading to a significantly improved faradaic efficiency. This journal is
- Ding, Mengning,Li, Xiaoshan,Sun, Yuxia,Xie, Jin,Xu, Wentao,Yang, Miao
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supporting information
p. 7543 - 7551
(2020/11/18)
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- Iodine(III)-catalyzed benzylic oxidation by using the (PhIO)n/Al(NO3)3 system
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The first iodine(III)-based procedure for the benzylic oxidation of different arenes is described by using the (PhIO)n/Al(NO3)3 system under catalytic conditions leading to the formation of the corresponding carbonyl derivatives. The method proceeds under mild, operationally simple, room temperature, short reaction times, and open flask conditions. In light of the organocatalysis relevance and the novelty of our protocol, we wish to communicate our initial results of this novel oxidation.
- Yahuaca-Juárez, Berencie,González, Gerardo,Ramírez-Morales, Marco A.,Alba-Betancourt, Calara,Deveze-álvarez, Martha A.,Mendoza-Macías, Claudia L.,Ortiz-Alvarado, Rafael,Juárez-Ornelas, Kevin A.,Solorio-Alvarado, César R.,Maruoka, Keiji
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p. 539 - 548
(2020/01/22)
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- Visible-Light-Triggered Quantitative Oxidation of 9,10-Dihydroanthracene to Anthraquinone by O2 under Mild Conditions
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The development of mild and efficient processes for the selective oxygenation of organic compounds by molecular oxygen (O2) is key for the synthesis of oxygenates. This paper discloses an atom-efficient synthesis protocol for the photo-oxygenation of 9,10-dihydroanthracene (DHA) by O2 to anthraquinone (AQ), which could achieve quantitative AQ yield (100 %) without any extra catalysts or additives under ambient temperature and pressure. A yield of 86.4 % AQ was obtained even in an air atmosphere. Furthermore, this protocol showed good compatibility for the photo-oxidation of several other compounds with similar structures to DHA. From a series of control experiments, free-radical quenching, and electron paramagnetic resonance spin-trapping results, the photo-oxygenation of DHA was probably initiated by its photoexcited state DHA*, and the latter could activate O2 to a superoxide anion radical (O2.?) through the transfer of its electron. Subsequently, this photo-oxidation was gradually dominated by the oxygenated product AQ as an active photocatalyst obtained from the oxidation of DHA by O2.?, and was accelerated with the rapid accumulation of AQ. The present photo-oxidation protocol is a good example of selective oxygenation based on the photoexcited substrate self-activated O2, which complies well with green chemistry ideals.
- Jiang, Dabo,Hu, Wenwei,Chen, Mengke,Fu, Zaihui,Su, Anqun,Yang, Bo,Mao, Feng,Zhang, Chao,Liu, Yachun,Yin, Dulin
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p. 1785 - 1792
(2020/03/13)
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- Functionalization of Zirconium-Based Metal–Organic Layers with Tailored Pore Environments for Heterogeneous Catalysis
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Intriguing properties and functions are expected to implant into metal–organic layers (MOLs) to achieve tailored pore environments and multiple functionalities owing to the synergies among multiple components. Herein, we demonstrate a facile one-pot synthetic strategy to incorporate multiple functionalities into stable zirconium MOLs via secondary ligand pillaring. Through the combination of Zr6-BTB (BTB=benzene-1,3,5-tribenzoate) layers and diverse secondary ligands (including ditopic and tetratopic linkers), 31 MOFs with multi-functionalities were systematically prepared. Notably, a metal–phthalocyanine fragment was successfully incorporated into this Zr-MOL system, giving rise to an ideal platform for the selective oxidation of anthracene. The organic functionalization of two-dimensional MOLs can generate tunable porous structures and environments, which may facilitate the excellent catalytic performance of as-synthesized materials.
- Dang, Dongbin,Lollar, Christina T.,Pang, Jiandong,Qiao, Guan-Yu,Qin, Jun-Sheng,Rao, Heng,Yu, Jihong,Yuan, Shuai,Zhou, Hong-Cai
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supporting information
p. 18224 - 18228
(2020/08/19)
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- Preparation method of anthraquinone and alkyl derivatives thereof
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The invention relates to the field of organic matter preparation, and discloses a preparation method of anthraquinone and alkyl derivatives thereof, and the method comprises the following steps: underacidic conditions, carrying out contact reaction on anthracene and alkyl derivatives thereof, an oxidant and a catalyst. The anthraquinone and the alkyl derivative thereof have a structure as shown in a formula (I) which is described in the specification. The catalyst comprises a carrier and metal elements loaded on the carrier, wherein the metal elements comprise molybdenum and tungsten, in theformula (I), R1 and R2 are each independently selected from hydrogen and substituted or unsubstituted C1-C10 hydrocarbon groups. The method provided by the invention has the characteristics of mild operation conditions and high product yield.
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Page/Page column 0139-0142; 0145-0154
(2020/08/18)
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- 9,10-Dihydroanthracene auto-photooxidation efficiently triggered photo-catalytic oxidation of organic compounds by molecular oxygen under visible light
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The development of mild and efficient process for the selective oxidation of organic compounds by molecular oxygen (O2) can be one of the key technologies for synthesizing oxygenates. This paper discloses an efficient and mild synthesis protocol for the O2-involved ethylbenzene (EB) photooxidation triggered by 910-dihydroanthracene (DHA) auto- photooxidation in acetone under visible light illumination, which can achieve 87.7 percent EB conversion and 99.5 percent acetylacetone (ACP) selectivity under ambient conditions. Also, 62.9 percent EB conversion and 96.3 percent ACP selectivity is obtained in air atmosphere. Furthermore, this protocol has a good adaptability for the photooxidation of other organic substrates such as tetrahydronaphthalene, diphenylmethane, toluene, cyclohexane, cyclohexene, alcohol, methylfuran and thioether to their corresponding oxygenates. A series of control and quenching tests, combined with EPR spectra, suggest that the photo-excited DHA can transfer its photo-electron to O2 to yield a superoxide radical anion (O2??), then DHA is preferentially oxidized to anthraquinone (AQ) by the active O2?? owing to its high reactivity. Finally, the in situ generated AQ as an active photo-catalyst can achieve the photooxidation of EB and other organic compounds by O2. The present photo-autoxidation protocol gives a good example for the O2-based selective oxidation of inert hydrocarbons under mild conditions.
- Chen, Mengke,Deng, Youer,Fu, Zaihui,Hu, Wenwei,Jiang, Dabo,Liu, Yachun,Mao, Feng,Su, Anqun,Yang, Bo,Zhang, Chao
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- Palladium aminopyridine complexes catalyzed selective benzylic C-H oxidations with peracetic acid
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Four palladium(ii) complexes with tripodal ligands of the tpa family (tpa = tris(2-pyridylmethyl)amine) have been synthesized and X-ray characterized. These complexes efficiently catalyze benzylic C-H oxidation of various substrates with peracetic acid, affording the corresponding ketones in high yields (up to 100%), at 1 mol% catalyst loadings. Complex [(tpa)Pd(OAc)](PF6) with the least sterically demanding ligand tpa demonstrates the highest substrate conversions and ketone selectivities. Preliminary mechanistic data provide evidence in favor of metal complex-mediated rate-limiting benzylic C-H bond cleavage by an electron-deficient oxidant.
- Bryliakov, Konstantin P.,Lubov, Dmitry P.,Lyakin, Oleg Yu.,Rybalova, Tatyana V.,Samsonenko, Denis G.,Talsi, Evgenii P.
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supporting information
p. 11150 - 11156
(2020/09/02)
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- Modified graphene supported Ag-Cu NPs with enhanced bimetallic synergistic effect in oxidation and Chan-Lam coupling reactions
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Herein, well dispersed Ag-Cu NPs supported on modified graphene have been synthesized via a facile and rapid approach using sodium borohydride as a reducing agent under ambient conditions. Dicyandiamide is selected as an effective nitrogen source with TiO2 as an inorganic material to form two kinds of supports, labelled as TiO2-NGO and NTiO2-GO. Initially, the surface area analysis of these two support materials was carried out which indicated that N-doping of GO followed by anchoring with TiO2 has produced support material of larger surface area. Using both types of supports, ten nano-metal catalysts based on Ag and Cu were synthesized. Benefiting from the bimetallic synergistic effect and larger specific surface area of TiO2-NGO, Cu?Ag-TiO2-NGO is found to be a highly active and reusable catalyst out of other synthesized catalysts. It exhibits excellent catalytic activity for oxidation of alcohols and hydrocarbons as well as Chan-Lam coupling reactions. The nanocatalyst is intensively characterized by BET, SEM, HR-TEM, ICP-AES, EDX, CHN, FT-IR, TGA, XRD and XPS. This journal is
- Choudhary, Anu,Gupta, Monika,Kaur, Manpreet,Paul, Satya,Sharma, Chandan,Sharma, Nitika
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p. 30048 - 30061
(2020/10/06)
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- Design, Synthesis, Molecular Docking, and Biological Evaluation of New Emodin Anthraquinone Derivatives as Potential Antitumor Substances
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The emodin anthraquinone derivatives are generally used in traditional Chinese medicine due to their various pharmacological activities. In the present study, a series of emodin anthraquinone derivatives have been designed and synthesized, among which 1,3-dihydroxy-6,8-dimethoxyanthracene-9,10-dione is a natural compound that has been synthesized for the very first time, and 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione is a compound that has never been reported earlier. Interestingly, while total seven of these compounds showed neuraminidase inhibitory activity in influenza virus with inhibition rate more than 50 %, specific four compounds exhibited significant inhibition of tumor cell proliferation. The further results demonstrate that 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione showed the best anticancer activity among all the synthesized compounds by inducing highest apoptosis rate to HCT116 cancer cells and arresting their G0/G1 cell cycle phase, through elevation of intracellular level of reactive oxygen species (ROS). Moreover, the binding of 1,3-dimethoxy-5,8-dimethylanthracene-9,10-dione with BSA protein has thoroughly been investigated. Altogether, this study suggests the neuraminidase inhibitory activity and antitumor potential of the new emodin anthraquinone derivatives.
- Li, Yuying,Guo, Fang,Chen, Tinggui,Zhang, Liwei,Wang, Zhuanhua,Su, Qiang,Feng, Liheng
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- High conversion and selectivity of photodimerization under air conditions by supramolecular oxidation restraint within a metallocage-like nanoreactor
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The well-designed metal-organic cage Ce-BHP, with a size-suitable cavity, functional interaction sites and a flexible backbone, could encapsulate 9-anthraldehyde molecules and act as a nanoreactor via supramolecular behavior, avoiding the undesired oxidation forming 9,10-anthraquinone, and also as an efficient catalyst to successfully achieve high conversion of single photodimers under air conditions. This journal is
- Dou, Yong,Qin, Lan,Wang, Suna,Yang, Lu,Zhang, Daopeng,Zhou, Zhen
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p. 5411 - 5415
(2020/09/03)
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- Solvent-free, microwave assisted oxidation of alcohols with 4-hydroxypyridinium chlorochromate functionalized silica gel
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4-Hydroxypyridinium chlorochromate functionalized silica gel was found to be an efficient and reusable oxidant for the very fast oxidation of primary and secondary alcohols to the corresponding carbonyl compounds under solventfree conditions and microwave irradiation in excellent yields.
- AHMADI, Sayed Ali,GHALEHBANDI, Shermineh Sadat,GHAZANFARI, Dadkhoda,SHEIKHHOSSEINI, Enayatollah
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p. 283 - 289
(2020/10/06)
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- Direct Exploitation of the Ethynyl Moiety in Calcium Carbide Through Sealed Ball Milling
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Ball milling of calcium carbide (CaC2) enables the reaction of its ethynyl moiety with organic electrophiles. This was realized simply by co-milling CaC2 with organic substrates in a sealed jar without the need for an additive or a catalyst. Various ketones including those bearing α-hydrogens were ethynylated in good yields at short reaction times. Aryl halides are also amenable substrates for this protocol as they furnish aryl ethynes through a benzyne intermediate. This method offers a practical and cheap alternative to the established procedures for introducing ethynyl functionalities.
- Hosseini, Abolfazl,Schreiner, Peter R.
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p. 4339 - 4346
(2020/07/04)
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- Fast Hydrocarbon Oxidation by a High-Valent Nickel–Fluoride Complex
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In the search for highly reactive oxidants we have identified high-valent metal–fluorides as a potential potent oxidant. The high-valent Ni–F complex [NiIII(F)(L)] (2, L=N,N′-(2,6-dimethylphenyl)-2,6-pyridinedicarboxamidate) was prepared from [NiII(F)(L)]? (1) by oxidation with selectfluor. Complexes 1 and 2 were characterized by using 1H/19F NMR, UV-vis, and EPR spectroscopies, mass spectrometry, and X-ray crystallography. Complex 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic data and products analysis demonstrate a hydrogen atom transfer mechanism of oxidation. The rate constant determined for the oxidation of 9,10-dihydroanthracene (k2=29 m?1 s?1) compared favorably with the most reactive high-valent metallo-oxidants. Complex 2 displayed reaction rates 2000–4500-fold enhanced with respect to [NiIII(Cl)(L)] and also displayed high kinetic isotope effect values. Oxidative hydrocarbon and phosphine fluorination was achieved. Our results provide an interesting direction in designing catalysts for hydrocarbon oxidation and fluorination.
- Lovisari, Marta,McDonald, Aidan R.,Mondal, Prasenjit,Twamley, Brendan
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supporting information
p. 13044 - 13050
(2020/06/05)
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- Highly Active and Robust Ruthenium Complexes Based on Hemilability of Hybrid Ligands for C-H Oxidation
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Evaluation of the hemilability of hybrid ligands provides a key to understand the metal-ligand cooperation in transition metal catalysis. Here, we design and synthesize a type of RuII complexes based on the hemilability of N-heterocyclic carbenes (NHCs), pyridine, and pyrazole, to compare their activity with other reported Ru catalysts in benzylic C-H oxidation. The RuII catalysts showed ultrastrong catalytic activity in water at room temperature and achieved a turnover frequency (TOF) of 114 h-1, which is the highest TOF value ever reported for Ru-catalyzed benzylic C-H oxidation. The addition of tridentate hybrid ligands in the Ru central position has two beneficial effects: NHCs with a stronger donor ability stabilize the Ru center; however, nitrogen ligands with a relatively weaker donor ability release from the Ru center, so that they induce a reaction. UV-vis, high-resolution electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectrometry, the trapping of radicals, and the density functional theory calculations (DFT) suggested that a cation catalyst L-RuII-tBuO2H is formed via the reaction between starting RuII catalysts and tert-butyl hydroperoxide, which further undergoes a cleavage of the O-O bond to generate a radical and a cation L-RuIII-OH active intermediate.
- Bo, Chun-Bo,Bu, Qingqing,Li, Xue,Ma, Ge,Wei, Donghui,Guo, Cheng,Dai, Bin,Liu, Ning
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p. 4324 - 4334
(2020/03/05)
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- Synthesis method of 9,10-anthraquinone
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The invention discloses a synthesis method of 9,10-anthraquinone. The method comprises the following steps: adding an organic solvent, water, 9-anthraboric acid and an alkali into a reaction vessel, and stirring for 1-2 h, wherein a molar ratio of the 9-anthraceneboronic acid to the alkali is 1:1 to 1:15; filtering after the color and fluorescence of the reaction solution completely disappear to obtain solid 9,10-anthraquinone; and washing the filtrate with a saturated salt solution, drying with anhydrous magnesium sulfate, filtering, and carrying out reduced pressure distillation to remove the solvent in order to obtain 9,10-anthraquinone in the filtrate. The synthesis method of the 9,10-anthraquinone is simple to operate, nitric acid does not need to be used as a reaction raw material, the requirement of high corrosion resistance of the nitric acid on corrosion resistance of equipment is avoided, the maintenance cost of the equipment is reduced, high-temperature heating is not needed, the reaction energy consumption is reduced, and reaction intermediate links, reaction time and production cost are reduced; and the reaction can be completely carried out, so that the yield can be greatly improved.
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Paragraph 0044-0091
(2020/05/01)
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- Expected and unexpected photoreactions of 9-(10-)substituted anthracene derivatives in cucurbit[: N] uril hosts
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By arranging substrates in a reaction ready state through noncovalent interactions, supramolecular nanoreactors/catalysts show high selectivity and/or rate acceleration features. Herein, we report the host-guest complexation of 9-(10-)substituted anthracene derivatives (G1-G3) with cucurbit[n]uril (CB[n], n = 8, 10), and the photoreactions of these derivatives in the presence of CB[n] hosts. Both CB[10] and CB[8] showed no obvious effects on the photoreaction of 9,10-disubstituted derivative G1. For G2 and G3, CB[10] operated as either a nanoreactor or catalyst (10%) for the photodimerization of two compounds with high selectivity and high yield. However, although CB[8] formed a 1 : 2 complex with G2, as also observed with CB[10], the photosolvolysis product (9-anthracenemethanol) was obtained quantitatively after photoirradiation of the CB[8]·2G2 complex. This unexpected photosolvolysis was rationalized by a plausible catalytic cycle in which anthracene acts as a photoremovable protecting group (PPG) and the carbonium ion intermediate is stabilized by CB[8].
- Hu, Xianchen,Liu, Fengbo,Liu, Simin,Zhang, Xiongzhi,Zhao, Zhiyong
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p. 4779 - 4785
(2020/06/18)
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- Effect of substituents on the fluorescence quenching of a few (anthracen-9-yl)methanamines
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This article deals with the photophysical properties of a few (anthracen-9-yl)methanamines. Analysis of absorption and the fluorescence emission spectra of these compounds indicated intramolecular photoinduced electron transfer leading to quenching of excited states, the efficiency of which depends on the geometrical constraints and electronic factors pertaining to the molecule. The decay kinetics studied using Time Correlated Single Photon Counting showed a bi-exponential decay indicating the involvement of two transient species in the excited state of these molecules. Also, we build up a relation between the rate of the photochemical reaction, free energy change and quenching of excited states.
- Haridas, Suja,Jacob, Jomon P.,Mallia, Rekha R.,Mathew, Rani
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- Hydrogen on Cobalt Phosphide
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Cobalt phosphide (CoP) is one of the most promising earth-abundant replacements for noble metal catalysts for the hydrogen evolution reaction (HER). Critical to HER is the binding of H atoms. While theoretical studies have computed preferred sites and energetics of hydrogen bound to transition metal phosphide surfaces, direct experimental studies are scarce. Herein, we describe measurements of stoichiometry and thermochemistry for hydrogen bound to CoP. We studied both mesoscale CoP particles, exhibiting phosphide surfaces after an acidic pretreatment, and colloidal CoP nanoparticles. Treatment with H2 introduced large amounts of reactive hydrogen to CoP, ca. 0.2 H per CoP unit, and on the order of one H per Co or P surface atom. This was quantified using alkyne hydrogenation and H-atom transfer reactions with phenoxy radicals. Reactive H atoms were even present on the as-prepared materials. On the basis of the reactivity of CoP with various molecular hydrogen donating and accepting reagents, the distribution of binding free energies for H atoms on CoP was estimated to be roughly 51-66 kcal mol-1 (δG°H 0 to -0.7 eV vs H2). Operando X-ray absorption spectroscopy gave preliminary indications about the structure of hydrogenated CoP, showing a slight lattice expansion and no significant change of the effective nuclear charge of Co under H2-flow. These results provide a new picture of catalytically active CoP, with a substantial amount of reactive H atoms. This is likely of fundamental relevance for its catalytic and electrocatalytic properties. Additionally, the approach developed here provides a roadmap to examine hydrogen on other materials.
- Delley, Murielle F.,Wu, Zishan,Mundy, M. Elizabeth,Ung, David,Cossairt, Brandi M.,Wang, Hailiang,Mayer, James M.
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p. 15390 - 15402
(2019/11/02)
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- Photoreaction of anthracenyl phosphine oxides: Usual reversible photo- and heat-induced emission switching, and unusual oxidative P&C bond cleavage
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Anthracenyl(diphenyl)phosphine oxide and dianthracenylphenylphosphine oxide as photoactive compounds have been synthesized. Anthracenyl group of these compounds indicate the multi-functional roles such as an emission component, a photodimerization component, and a leaving group. When the light irradiation was performed under an oxygen atmosphere, photo-oxidative P&C bond cleavage to leave the antharacenyl group was observed. Moreover, phosphonyl radical was produced and then P&P bond formation to form diphosphane was observed.
- Katagiri, Kosuke,Yamamoto, Yukina,Takahata, Yuui,Kishibe,Fujimoto
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p. 2026 - 2029
(2019/07/03)
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- Dibenzo[b,e]aza-6,11-diketotriazole compound as well as preparation method and application thereof
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The invention provides a dibenzo[b,e]aza-6,11-diketotriazole compound and a preparation method thereof, belongs to the technical field of medicines, and specifically relates to a 5-((1-(R-phenyl)-1H-1,2,3-triazol-4-yl)methyl)-5H-dibenzo[b,e]aze-6,11-diketone anti-tumor compound as well as a preparation method and application thereof. The compound prepared by the invention has a function of inhibiting tumor activity and has excellent application prospect in the field of design, research and development of anti-tumor drugs; in addition, the preparation method is simple and easy to industrialize.
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Paragraph 0060; 0064; 0065
(2019/09/05)
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- Method for driving molecular oxygen to selectively oxidize 9,10-dihydroanthracene and quantitatively convert 9,10-dihydroanthracene into anthraquinone by visible light
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The invention relates to the technical field of photooxidation synthesis, and discloses a simple, convenient and practical visible light synthesis method for quantitatively converting 9, 10-dihydroanthracene into anthraquinone based on molecular oxygen selective oxidation. Under a condition of normal temperature, normal pressure, pure oxygen atmosphere and no catalysts and additives, the synthesismethod can realize 100% raw material conversion and provide a anthraquinone yield of 99.3%, and 86.4% of anthraquinone yield can be obtained even in an air atmosphere. Moreover, the synthesis methodalso shows a good effect on photooxidation of other compounds with structures similar to the structure of 9, 10-dihydroanthracene, and the synthesis method is indicated to have relatively wide applicability. The visible light synthesis method provided by the invention provides a very good example for participation of active O2 of a substrate in selective oxidation, and accords with the concept ofgreen chemistry.
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Paragraph 0017-0026
(2020/01/03)
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- Magnetically recoverable graphene oxide supported Co@Fe3O4/L-dopa for C-C cross-coupling and oxidation reactions in aqueous medium
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We report the synthesis of inexpensive and environmentally benign cobalt(0) nanoparticles on L-3,4-dihydroxyphenylalanine (L-dopa) functionalized and magnetite (Fe3O4) grafted graphene oxide (Co@GO/Fe3O4/L-dopa) which was fully characterized with different techniques such as Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Photoelectron Spectroscopy (XPS), X-ray Powder Diffraction (XRD), Thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM), Carbon Hydrogen Nitrogen (CHN) analysis, Energy Dispersive X-ray (EDX) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES). Graphene oxide was used as the core material due to its mechanical, electrical and thermal properties. In order to avoid the cumbersome process of separation, magnetite nanoparticles were coated over the graphene oxide. After the successful preparation of graphene oxide based magnetic nanoparticles, L-dopa was grafted over Fe3O4 nanoparticles so as to provide firm anchoring agent for cobalt nanoparticles. Finally, cobalt(0) nanoparticles were immobilized on the developed magnetic support. The catalytic efficiency of the synthesized catalyst was tested for Suzuki cross-coupling and oxidation reactions, usually carried out by precious and expensive second and third row transition metals; products were obtained in good to excellent yields. The synthesized catalyst represents an attractive alternative to conventional catalysts for Suzuki cross-coupling and oxidation reactions, and is recyclable up to five runs.
- Sharma, Harsha,Sharma, Shally,Sharma, Chandan,Paul, Satya,Clark, James H.
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- 2-Iodoxybenzoic acid ditriflate: The most powerful hypervalent iodine(v) oxidant
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A ditriflate derivative of 2-iodoxybenzoic acid (IBX) was prepared by the reaction of IBX with trifluoromethanesulfonic acid and characterized by single crystal X-ray crystallography. IBX-ditriflate is the most powerful oxidant in a series of structurally similar IBX derivatives which is best illustrated by its ability to readily oxidize hydrocarbons and the oxidation resistant polyfluoroalcohols.
- Yusubov, Mekhman S.,Soldatova, Natalia S.,Postnikov, Pavel S.,Valiev, Rashid R.,Yoshimura, Akira,Wirth, Thomas,Nemykin, Victor N.,Zhdankin, Viktor V.
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supporting information
p. 7760 - 7763
(2019/07/12)
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- Iron-Decorated, Guanidine Functionalized Metal-Organic Framework as a Non-heme Iron-Based Enzyme Mimic System for Catalytic Oxidation of Organic Substrates
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A novel porous functionalized metal-organic framework (MOF) as a non-heme iron-based enzyme mimic system was achieved via two-step post-synthetic modification of the MIL-101(Cr)-NH2, and characterized by FT-IR, PXRD, TGA, SEM, EDS, CHN, BET surface area, and ICP-OES analyses. This new modified MOF (MIL-101(Cr)-guanidine-Fe) has been demonstrated to be a highly efficient, active, and reusable catalyst for oxidation of various organic substrates, including alcohols, alkenes and alkyl arenes at room temperature using H2O2 as an oxidant. Graphical Abstract: [Figure not available: see fulltext.].
- Shaabani, Ahmad,Mohammadian, Reza,Farhid, Hassan,Karimi Alavijeh, Masoumeh,Amini, Mostafa M.
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p. 1237 - 1249
(2019/03/13)
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- Evolution of physical and photocatalytic properties of new Zn(II) and Ru(II) complexes
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Synthesis of Zn(II) and Ru(II) complexes were reported by using N4-macrocyclic Schiff base ligands under solvothermal conditions. The newly synthesized Zn(II) and Ru(II) complexes have been characterized by various physico-chemical techniques such as elemental analysis, molar conductance, HRMS, TGA, FESEM, UV–Vis, FT-IR, 1H NMR, and cyclic voltammetry. By using molar conductance studies, the complexes are formulated as [Zn(TPTTP)]Cl2 and [Ru(TPTTP)Cl2]. C–H bond activation of an sp3 group of methylstyrenes (converted into cinnamaldehydes) and C–H bond activation of the sp2 bond of polycyclic aromatic hydrocarbons through photooxidation was examined in the presence of Zn(II) and Ru(II) complexes. Reusable activity studies and photostability of catalyst are investigated by using UV–Vis spectra. Based on the results, higher catalytic activity of [Ru(TPTTP)Cl2] complex than [Zn(TPTTP)]Cl2 complex in both C–H bond activation and photooxidation of aromatic hydrocarbons has been reported.
- Gugulothu, Venkanna,Ahemed, Jakeer,Subburu, Mahesh,Yadagiri, Bhongiri,Mittal, Ritu,Prabhakar, Chetti,Pola, Someshwar
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p. 412 - 423
(2019/06/27)
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- Electrochemical benzylic oxidation of C-H bonds
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Oxidized products have become increasingly valuable as building blocks for a wide variety of different processes and fine chemistry, especially in the benzylic position. We report herein a sustainable protocol for this transformation through C-H functionalization and is performed using electrochemistry as the main power source and tert-butyl hydroperoxide as the radical source for the C-H abstraction. The temperature conditions reported here do not increase above 50 °C and use an aqueous-based medium. A broad substrate scope is explored, along with bioactive molecules, to give comparable and increased product yields when compared to prior reported literature without the use of electrochemistry.
- Marko, Jason A.,Durgham, Anthony,Bretz, Stacey Lowery,Liu, Wei
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supporting information
p. 937 - 940
(2019/01/23)
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- Photochemical reaction of anthracene with dioxygen catalyzed by platinum(II) porphyrin
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Visible light irradiation of anthracene in the presence of platinum(II) porphyrin (PtPor) and dioxygen affords anthraquinone as the main product. This reaction involves two steps: the [4+2]cycloaddition of anthracene with singlet oxygen to afford anthracene-9,10-endoperoxide and the degradation of endoperoxide. PtPor catalyzes both reactions.
- Yamashita, Ken-ichi,Sugiura, Ken-ichi
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supporting information
(2019/09/04)
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- Controlled Photocatalytic Hydrocarbon Oxidation by Uranyl Complexes
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Controlled, photocatalytic C?H bond activations are key reactions in the toolkits of the modern synthetic chemist. While it is known that the uranyl(VI) ion, [UVIO2]2+, the environmentally dominant form of uranium, is photoactive, most literature examines its luminescent properties, neglecting its potential synthetic utility for photocatalytic C?H bond cleavage. Here, we synthesise and fully characterise an air-stable and hydrocarbon-soluble uranyl phenanthroline complex, [UVIO2(NO3)2(Ph2phen)], UPh2phen, and demonstrate that it can catalytically abstract hydrogen atoms from a variety of organic substrates under visible light irradiation. We show that the commercially available parent complex, uranyl nitrate ([UVIO2(NO3)2(OH2)2]?4H2O; UNO3), is also competent, but from electronic spectroscopy we attribute the higher rates and selectivity of UPh2phen to ligand-mediated electronic effects. Ketones are selectively formed over other oxygenated products (alcohols, etc.), and the catalytic oxidation of substrates containing a benzylic C?H position is particularly improved for UPh2phen. We also show uranyl-mediated photocatalytic C?C bond cleavage in a model lignin compound for the first time.
- Arnold, Polly L.,Purkis, Jamie M.,Rutkauskaite, Ryte,Kovacs, Daniel,Love, Jason B.,Austin, Jonathan
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p. 3786 - 3790
(2019/03/07)
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