- A polyoxometalate@covalent triazine framework as a robust electrocatalyst for selective benzyl alcohol oxidation coupled with hydrogen production
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Electrocatalytic oxidation has been proven as a sustainable and promising alternative to traditional chemical transformation, but its further development is limited by the use of noble-metal electrocatalysts. Herein, a polyoxometalate-based electrode material,H5PMo10V2O40@CTF(denoted asPMo10V2@CTF), has been successfully fabricated through electrostatic assembly of a molecular polyoxometalate catalyst,PMo10V2, with a porous cationic covalent triazine framework (CTF), which, to our knowledge, represents the first combination of polyoxometalate with a cationic CTF. The resultingPMo10V2@CTFexhibits high activity for the selective electrocatalytic oxidation of alcohols to aldehydes, achieving 99% conversion of benzyl alcohol, over 99% selectivity of benzyl aldehyde, and at the same time near unity H2production. Notably, the reported electrocatalytic system presents good atom economy, high energy conversion (96% faradaic efficiency), remarkable catalytic activity and robustness for at least eight recycles. Based on the various experimental and spectroscopic analyses, a possible catalytic mechanism was proposed, revealing that such excellent electrocatalytic performance is attributed to the versatile redox ability ofPMo10V2and the good porosity and adsorption property of the CTF in the constructedPMo10V2@CTFcomposite.
- Li, Zhen,Zhang, Junhao,Jing, Xiaoting,Dong, Jing,Liu, Huifang,Lv, Hongjin,Chi, Yingnan,Hu, Changwen
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- Comparison of selective oxidation of aromatic alcohols using copper(II) chromite-titanium dioxide nanocomposite at reflux, light irradiation, and microwave conditions
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CuCr2O4/TiO2 nanocomposites with different TiO2 contents were synthesized by using sol-gel method. Products were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Results demonstrated a cubic normal spinel structure for copper (2+) chromite, with the particle sizes of about 25–40 nm. Activities of CuCr2O4 nanopowders and CuCr2O4/TiO2 nanocomposite were tested for oxidation of benzylic alcohols to aldehydes at reflux, light irradiation, and microwave conditions. The influence of some parameters on the oxidation of alcohol, such as optimum molar ratio of chromite to titanium dioxide, catalyst dosage, and type and amount of oxidant and solvents (dichloromethane, acetonitrile, and ethanol) was studied to determine the optimal operating conditions for alcohol oxidation in reflux, light irradiation, and microwave conditions.
- Shojaei, Abdollah Fallah,Shirini, Farhad,Hedayati, Elaheh
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- Gold nanoparticles supported on Cs2CO3 as recyclable catalyst system for selective aerobic oxidation of alcohols at room temperature
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NaAuCl4/Cs2CO3 was found to be a simple bench top, recyclable and selective catalyst system for the aerobic oxidation of various types of alcohols into their corresponding aldehydes and ketones at room temperature without the need for any further polymeric and/or oxidic support.
- Karimi, Babak,Kabiri Esfahani, Farhad
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- A chloro bridged Cu(II)-Cu(II) complex of a new aminophenol ligand: Magnetostructural, radical decay kinetic studies, highly efficient and aerial alcohol oxidation
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A new tripodal aminophenol-based ligand containing a pyridine unit was synthesized and characterized by IR and 1H NMR spectroscopic techniques. A dimeric copper(II) complex of this ligand was prepared and characterized by X-ray crystallography, DFT calculations, spectroscopic techniques and magnetic susceptibility measurements. X-ray analysis revealed a complex in which one phenolate, and amine and imine nitrogens of the ligand are arranged in a distorted square pyramidal geometry (SP) around the copper ions. Two chloride bridges hold both copper atoms together to form the binuclear [LAphCuCl]2 complex. This complex exhibits nearly no superexchange coupling between the copper centers. The phenolate moieties of the copper complex were electrochemically oxidized to phenoxyl radical cations [LAphCuCl]2+. The decay kinetics of the mentioned radical were investigated using a simulation of the voltammogram data. In addition, highly efficient and eco-friendly oxidation of alcohols to aldehydes was achieved with molecular oxygen or air as the oxidant and the [LAphCuCl]2-Cs2CO3 system as a catalyst.
- Balaghi, S. Esmael,Safaei, Elham,Rafiee, Mohammad,Kowsari, Mohammad Hossein
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- Design and development of natural and biocompatible raffinose-Cu2O magnetic nanoparticles as a heterogeneous nanocatalyst for the selective oxidation of alcohols
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Natural polymers are recently playing a vital role as a support for the noble metals. In the present study, raffinose from the classes of oligosaccharide polymer with a high capacity of magnetization was used as active support for the copper metal. The copper immobilized on the raffinose-based magnetic nanoparticles (MNPs) which can be used as a recyclable heterogeneous nanocatalyst for the selective oxidation of primary benzyl alcohols (PBA) to benzaldehyde (BAD) derivatives. The morphology and structure of the recoverable magnetic nanocatalyst were characterized using different microscopic and spectroscopic techniques including FT-IR, GC, VSM, XRD, TEM, TGA, FESEM and EDS analyses. Also, the optimum conditions of co-reactant, reaction time, oxidant, temperature and amount of the nanocatalyst for oxidation reaction were investigated. Moreover, the Fe3O4?raffinose-Cu2O NPs had a significant effect to enhance yield and reduce the reaction time.
- Eivazzadeh-Keihan, Reza,Esmaeili, Mir Saeed,Ghafuri, Hossein,Maleki, Ali,Varzi, Zahra
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- Bimetallic synergistic Au/CuO-hydroxyapatite catalyst for aerobic oxidation of alcohols
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A catalyst consisting of Au supported on copper oxide-modified hydroxyapatite (Au/CuO-HAP) was prepared using a homogeneous deposition-precipitation method. The catalyst was characterized using atomic absorption spectrometry, N2 adsorption-desorption, powder X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalytic performance in liquid-phase aerobic oxidation of alcohols was investigated. The catalytic activity and benzaldehyde selectivity in benzyl alcohol oxidation with the bimetallic Au/CuO-HAP catalyst were significantly better than those with monometallic Au/HAP and CuO-HAP catalysts. The conversion of benzyl alcohol and selectivity for benzaldehyde at 120 °C for 1.5 h under aerobic oxidation conditions were 99.7% and 98.4%, respectively. Various aromatic alcohols were selectively converted to their corresponding aldehydes or ketones over Au/CuO-HAP. The Au/CuO-HAP catalyst could be reused at least four times without loss of activity.
- Tian, Tao,Liu, Ying,Zhang, Xungao
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- Preparation of large-size, superparamagnetic, and highly magnetic Fe3O4@PDA core-shell submicrosphere-supported nano-palladium catalyst and its application to aldehyde preparation through oxidative dehydrogenation of benzyl alcohols
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Large-size, superparamagnetic, and highly magnetic Fe3O4@PDA core-shell submicrospheresupported nano-palladium catalysts were prepared in this study. Dopamine was encapsulated on the surface of Fe3O4 particles via self-polymerization and then protonated to positively charge the microspheres. PdCl42- was dispersed on the surface of the microspheres by positive and negative charge attraction and then reduced to nano-palladium. With air as oxidant, the catalyst can successfully catalyze the dehydrogenation of benzyl alcohols to produce the corresponding aldehydes at 120 °C.
- Guo, Haichang,Zheng, Renhua,Jiang, Huajiang,Xu, Zhenyuan,Xia, Aibao
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- Three new imidazole-functionalized hexanuclear oxidovanadium clusters with exceptional catalytic oxidation properties for alcohols
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Cluster cat: Three new imidazole-functionalized neutral hexanuclear vanadium clusters have been prepared, one of which shows exceptional catalytic activity in the selective aerobic oxidation of alcohols (see scheme). Furthermore, these new polyoxovanadium clusters can be readily recycled and reused with unchanged catalytic activity. A plausible catalytic cycle is also proposed. Copyright
- Chen, Baokuan,Huang, Xianqiang,Wang, Boe,Lin, Zhengguo,Hu, Jufang,Chi, Yingnan,Hu, Changwen
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- Multifunctional radical-doped polyoxometalate-based host-guest material: Photochromism and photocatalytic activity
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An effective strategy to synthesize multifunctional materials is the incorporation of functional organic moieties and metal oxide clusters via self-assembly. A rare multifunctional radical-doped zinc-based host-guest crystalline material was synthesized with a fast-responsive reversible ultraviolet visible light photochromism, photocontrolled tunable luminescence, and highly selective photocatalytic oxidation of benzylic alcohols as a result of blending of distinctively different functional components, naphthalenediimide tectons, and polyoxometalates (POMs). It is highly unique to link π-electron-deficient organic tectons and POMs by unusual POMs anion-π interactions, which are not only conducive to keeping the independence of each component but also effectively promoting the charge transfer or exchange among the components to realize the fast-responsive photochromism, photocontrolled tunable luminescence, and photocatalytic activity.
- Liao, Jian-Zhen,Zhang, Hai-Long,Wang, Sa-Sa,Yong, Jian-Ping,Wu, Xiao-Yuan,Yu, Rongmin,Lu, Can-Zhong
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- Tuning of the redox potential and catalytic activity of a new Cu(ii) complex by: O -iminobenzosemiquinone as an electron-reservoir ligand
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The synthesis and characterization of a new Cu(ii) complex, LNIS2CuII (LNIS = o-iminobenzosemiquinone), are reported. X-ray crystallography studies showed that two o-iminobenzosemiquinone radicals form a distorted square-planar geometry around the Cu(ii) center of LNIS2CuII. Magnetic measurements revealed the paramagnetic character of the complex caused by the presence of three unpaired electrons located on the o-iminobenzosemiquinonate ligands and the CuII center. Magnetochemical experiments, and EPR and DFT studies prove that the ground state of the complex is a doublet, which is consistent with the ferromagnetic coupling between Cu(ii) and o-iminobenzosemiquinone centers and stronger antiferromagnetic coupling between the iminobenzosemiquinone moieties. The ligand-centered redox reactions of the complex were studied by cyclic voltammetry. Aerobic oxidation of alcohols to aldehydes with TEMPO was studied in the presence of LNIS2CuII. Furthermore, LNIS2CuII was found to be an efficient catalyst in homo-coupling of terminal alkynes.
- Nasibipour, Mina,Safaei, Elham,Wrzeszcz, Grzegorz,Wojtczak, Andrzej
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- TEMPO-mediated aerobic oxidation of alcohols using copper(II) complex of bis(phenol) di-amine ligand as biomimetic model for Galactose oxidase enzyme
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Mononuclear copper complexes of four-dentate N2O2 bis(phenol) diamine ligands (H2LNEX X: C and OB in which C and OB are chloro and tert-butyl-methoxy substituents on phenol groups) have been synthesized and characterized by IR, UV-Vis, single crystal X-ray diffraction, magnetic susceptibility studies and cyclic voltammetry techniques. The CuLNEX complexes show the square pyramid geometry of the coordination sphere with the copper centers surrounded by two nitrogen and oxygen atoms from the coordinating ligand and an axially bound water molecule. The effective magnetic moments of 1.7 and 1.8 BM confirm a monomer complex with copper(II) center. Electrochemical oxidation of these complexes yielded the corresponding Cu(II)-phenoxyl radical species. In addition, CuLNEX complexes, have shown efficient catalytic activities for TEMPO-mediated oxidation of a set of alcohols to the corresponding aldehydes in the presence of molecular oxygen as oxidant at room temperature.
- Safaei, Elham,Hajikhanmirzaei, Leila,Karimi, Babak,Wojtczak, Andrzej,Coti?, Patricia,Lee, Yong-Ill
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- An expeditious and efficient method for the oxidation of benzyl alcohols by homogeneous electrolysis
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A greener and inexpensive electrochemical method has been developed for the oxidation of benzyl alcohols by homogeneous electrolysis. The electrochemical reaction was carried out in an undivided cell equipped with carbon and stainless steel electrodes at room temperature. The homogeneous solution made up of acetonitrile/water containing substrate and ammonium bromide with a catalytic amount of H2SO4 as supporting electrolyte. The reaction condition was optimized with various electrochemical experimental parameters and evaluated with various substituted benzyl alcohols to result in excellent yield of aldehydes (>83%).
- Jagatheesan, Rathinavel,Shanmugavelan, Poovan,Sambathkumar, Subramaniyan,Ramesh, Pugalenthi
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- Protonated Pteridine and Flavin Analogues acting as Efficient and Substrate-selective Photocatalysts in the Oxidation of Benzyl Alcohol Derivatives by Oxygen
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Protonated aminopterin, lumazine, and riboflavin-tetra-acetate efficiently catalyse the substrate selective photo-oxidation of benzyl alcohol derivatives by oxygen in the presence of perchloric acid in acetonitrile at 298 K.
- Fukuzumi, Shunichi,Tanii, Kumiko,Tanaka, Toshio
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- Transformations of (-)-myrtenal epoxide over askanite-bentonite clay
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Acid-catalyzed transformations of (-)-myrtenal epoxide over askanite-bentonite clay involve skeletal rearrangements of the pinane framework, leading to an optically active dialdehyde (an analog of campholenic aldehyde), aldehydes having a p-menthane skeleton, and an unusual optically active aldehyde with a bicyclo[3.2.1]octene skeleton.
- Il'ina,Volcho,Korchagina,Barkhash,Salakhutdinov
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- A copper complex of a noninnocent iminophenol-amidopyridine hybrid ligand: Synthesis, characterization, and aerobic alcohol oxidation
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Reaction of the noninnocent iminophenol-iminopyridine hybrid ligand HLIPIP, where LIPIP denotes [2-((E)-{(E)-2-[(E)-pyridin-2-ylmethyleneamino]benzylidene}amino)-4,6-di-tert-butylphenolate], with copper acetate afforded a copper complex, LAPIPCuII, in which one of the imine functional groups is oxidized to an amide during metal complexation. The new CuII complex is capable of catalyzing efficient aerobic alcohol oxidation under mild conditions. The crystal structure of LAPIPCuII exhibits a square-planar geometry with the CuII center coordinated by three nitrogen atoms and one oxygen atom. Electrochemical studies were conducted to evaluate the redox-active behavior of the complex, and the results showed a quasireversible reduction and a ligand-based oxidation process. The neutral species of LAPIPCuII is EPR active, which is consistent with a paramagnetic electronic ground state (d9, S = 1/2), whereas the one-electron oxidized complex was X-band EPR silent. One-electron chemical oxidation of LAPIPCuII gave a new species that can be attributed to a CuII-phenoxyl radical complex. Based on EPR measurements in conjunction with density functional theory calculations, [LAPIPCuII]+ is proposed to have a triplet electronic ground state, exhibiting a weak ferromagnetic interaction between the CuII center and the coordinated phenoxyl radical. A new copper complex of a noninnocent iminophenol-pyridine hybrid ligand that is capable of efficient aerobic alcohol oxidation was studied.
- Alaji, Zahra,Safaei, Elham,Chiang, Linus,Clarke, Ryan M.,Mu, Changhua,Storr, Tim
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- Binary Pd-polyoxometalates and isolation of a ternary Pd-V-polyoxomolybdate active species for selective aerobic oxidation of alcohols
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Binary Pd-polyoxometalates [Pd(dpa)2]3[PW 12O40]2×12 DMSO (2), [Pd(dpa) 2]3[PMo12O40]2×12 DMSO×2 H2O (3), and [Pd(dpa)(DMSO)2] 2[HPMo10V2O40]×4 DMSO (4) were synthesized by reaction of [Pd(dpa)(OAc)2]×2 H2O (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][PMo12O40]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. Binary noble metal-POM compounds: The unprecedented ternary Pd-V-POM compound (POM=polyoxometalate) [Pd(dpa)2{VO(DMSO) 5}2][PMo12O40]2×4 DMSO, which was isolated during the catalytic recycling of [Pd(dpa)(DMSO) 2]2[HPMo10V2O40]×4 DMSO (dpa=2,2′-dipyridylamine) and characterized by single-crystal X-ray diffraction, proved to be the true active species and showed high catalytic activity for the aerobic oxidation of aromatic alcohols (see figure). Copyright
- Huang, Xianqiang,Zhang, Xiaomei,Zhang, Dan,Yang, Song,Feng, Xiao,Li, Jikun,Lin, Zhengguo,Cao, Jie,Pan, Ran,Chi, Yingnan,Wang, Bo,Hu, Changwen
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- Efficient and Reusable Sn(II)-containing Imidazolium-based Ionic Liquid as a Catalyst for the Oxidation of Benzyl Alcohol
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A simple and efficient catalytic system [BBIM]Br–SnCl2 for the oxidation of benzyl alcohol using hydrogen peroxide as the oxidant has been developed. Reaction conditions such as the catalyst dose, the solvents, reaction temperature, reaction time, and the amount of hydrogen peroxide were investigated. The optimum reaction conditions identified were 0.11 g of catalyst, no solvent, 65°C, 15 min, and 2 mmol of hydrogen peroxide. Oxidation of various alcohols was also investigated under the optimized conditions. The catalyst [BBIM]Br–SnCl2 can be easily recovered and reused for six reaction runs without significant loss of catalytic activity, because the Sn species of the catalyst can be coordinated with the imidazole ring of the ionic liquid. The reused catalyst was further characterized by Fourier transform infrared spectroscopy to evaluate its chemical properties. The results proved that the [BBIM]Br–SnCl2 catalyst was stable and reusable for the oxidation reactions. A possible mechanism for the oxidation of benzyl alcohol to benzaldehyde is proposed.
- Wang, Bingtong,Hu, Yulin,Fang, Dong,Wu, Lin,Xing, Rong
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- Micelle-enhancing effect on a flavin-photosensitized reaction of benzyl alcohols in aqueous solution
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The tetra-O-acetylriboflavin (Fl)-photosensitized dehydrogenation of benzyl alcohols 1 proceeded more efficiently in aqueous solutions in the presence of sodium dodecyl sulfate (H2O/SDS) than acetonitrile solutions. The fluorescence quenching of Fl with 1 occurred efficiently in H2O/SDS. The apparent rate constants (kQ) for the fluorescence quenching were determined by Stern-Volmer plots. The plots of kQ vs the free-energy changes for the electron transfer from 1 to the excited singlet of Fl showed the Rehm-Weller-type correlation. However, plots for H2/SDS were deviated from a curve calculated by the Rehm-Weller equation, although plots for MeCN were fitted to the calculated curve. The deviation in H2O/SDS is attributable to the incorporation of Fl and 1 into the hydrophobic domain of the SDS micelle, where the condensation, less-polar medium, and exteior negative charge operate favorably for efficient electron transfer.
- Yasuda, Masahide,Nakai, Takuya,Kawahito, Yasumasa,Shiragami, Tsutomu
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- Substrate-selective Photo-oxidation of Benzyl Alcohol Derivatives with Oxygen, catalysed by an NAD+ Model Compound
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An NAD+ model compound, 10-methylacridinium ion (AcrH+), catalyses the substrate-selective photo-oxidation of benzyl alcohol derivatives with oxygen in acetonitrile at 298 K, which is initiated by the electron-transfer reactions from benzyl alcohol derivatives to the singlet excited state of AcrH+.
- Fukuzumi, Shunichi,Kuroda, Sadaki,Tanaka, Toshio
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- Synthesis, characterization and study of catalytic activity of Silver doped ZnO nanocomposite as an efficient catalyst for selective oxidation of benzyl alcohol
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Powder samples of Ag/ZnO nanocomposite containing different amounts of Ag were synthesized by co-precipitation method. The synthesized samples were characterized by XRD, SEM, EDX and TEM techniques. The XRD results revealed that all the samples show wurtzite hexagonal phase of ZnO. The TEM micrographs of the samples showed that size of Ag-ZnO nanoparticles was in the range of 30-50 nm. Catalytic activity was tested using liquid-phase selective oxidation of benzylic alcohols to aldehydes. The influence of some parameters such as optimum weight of Ag, catalyst dosage, oxidant and various solvents were studied. The superior catalytic performance of the Ag/ZnO nanocomposite was observed in microwave condition compared to that performed in reflux condition. The catalysts were recycled three times in the oxidation of alcohols and little change in the conversion efficiency was observed. The highly dispersed Ag metal particles on ZnO surface was considered to be responsible for the catalytic activity. [Figure not available: see fulltext.]
- Shojaei, A. Fallah,Tabatabaeian,Zanjanchi,Moafi, H. Fallah,Modirpanah
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- On the stabilization of gold nanoparticles over silica-based magnetic supports modified with organosilanes
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The immobilization of gold nanoparticles (Au NPs) on silica is made possible by the functionalization of the silica surfaces with organosilanes. Au NPs could only be stabilized and firmly attached to silica-support surfaces that were previously modified with amino groups. Au NPs could not be stabilized on bare silica surfaces and most of the NPs were then found in the solution. The metal-support interactions before and after the Au NP formation, observed by X-ray absorption fine structure spectroscopy (XAFS), indicate a stronger interaction of gold(III) ions with amino-modified silica surfaces than with the silanol groups in bare silica. An amino-modified, silica-based, magnetic support was used to prepare an active Au NP catalyst for the chemoselective oxidation of alcohols, a reaction of great interest for the fine chemical industry.
- Oliveira, Rafael L.,Zanchet, Daniela,Kiyohara, Pedro K.,Rossi, Liane M.
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- An efficient and selective oxidation of benzylic and aromatic allylic alcohols with manganese dioxide supported on kieselguhr under solvent-free conditions
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An efficient and selective oxidation of benzylic and aromatic allylic alcohols to the corresponding aldehydes and ketones with manganese dioxide supported on kieselguhr at 50-55 C under solvent-free conditions in yields between 82 and 96 % is described. All the reactions are completed within 4 h. The merits of the present procedure by comparing with those reporting manganese dioxide oxidation are listed and the possible oxidation mechanism is also described. Aliphatic primary alcohols remain intact by this method.
- Zhu, Li-Yun,Lou, Zhiyuan,Lin, Jianan,Zheng, Wenjin,Zhang, Changhe,Lou, Ji-Dong
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- Creation of a high-valent manganese species on hydrotalcite and its application to the catalytic aerobic oxidation of alcohols
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A high-valent Mn oxide species is successfully synthesized on the surface of hydrotalcite (Mn/HT-Ox), and is found to act as an efficient heterogeneous catalyst for the oxidation of alcohols using molecular oxygen as an oxidant.
- Nagashima, Kohji,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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- Controllable synthesis, characterization, and catalytic properties of three inorganic-organic hybrid copper vanadates in the highly selective oxidation of sulfides and alcohols
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Three novel inorganic-organic hybrid copper vanadates α-[Cu(mIM)4]V2O6 (1), β-[Cu(mIM)4]V2O6 (2), and [Cu(mIM)2)](VO3)2 (3) (mIM = 1-methylimidazole) have been synthesized by rationally controlling of the hydrothermal conditions and fully characterized by single-crystal XRD, powder XRD, elemental analyses, TGA, and FT-IR spectroscopy. Interestingly, compounds 1 and 2 were isolated as geometric isomers by tuning the solvothermal reaction temperature. Because of the different coordination modes between the tetradentate [V4O12]4- and [Cu(mIM)4]2+ subunits, the supramolecular structures of the two isomers show a 3D framework with an interpenetrating diamond topology for 1 and a 2D network for 2, respectively. Compound 3 was obtained by tuning the reaction temperature and the ratio of mIM/H2O, which showed interesting left- and right-handed helixes with an identical pitch of ca. 5.388 ? in its 2D network structure. As heterogeneous catalysts, compounds 1-3 exhibit excellent catalytic performance in the oxidation of sulfides with H2O2 as oxidant. Among them, the catalytic activity of 1 (conv. up to 98.7%, sele. up to 100%) outperforms others and can be reused without losing its activity. The activity of 1 is also investigated in the oxidation of various alcohols, and excellent results (conv. up to 98.5%, sele. up to 100%) are obtained.
- Li, Jikun,Huang, Xianqiang,Yang, Song,Xu, Yanqing,Hu, Changwen
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- Maximizing the Number of Interfacial Sites in Single-Atom Catalysts for the Highly Selective, Solvent-Free Oxidation of Primary Alcohols
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The solvent-free selective oxidation of alcohols to aldehydes with molecular oxygen is highly attractive yet challenging. Interfacial sites between a metal and an oxide support are crucial in determining the activity and selectivity of such heterogeneous catalysts. Herein, we demonstrate that the use of supported single-atom catalysts (SACs) leads to high activity and selectivity in this reaction. The significantly increased number of interfacial sites, resulting from the presence of individually dispersed metal atoms on the support, renders SACs one or two orders of magnitude more active than the corresponding nanoparticle (NP) catalysts. Lattice oxygen atoms activated at interfacial sites were found to be more selective than O2 activated on metal NPs in oxidizing the alcohol substrate. This work demonstrates for the first time that the number of interfacial sites is maximized in SACs, providing a new avenue for improving catalytic performance by developing appropriate SACs for alcohol oxidation and other reactions occurring at metal–support interfacial sites.
- Li, Tianbo,Liu, Fei,Tang, Yan,Li, Lin,Miao, Shu,Su, Yang,Zhang, Junying,Huang, Jiahui,Sun, Hui,Haruta, Masatake,Wang, Aiqin,Qiao, Botao,Li, Jun,Zhang, Tao
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- 12-Molybdophosphoric acid anchored on aminopropylsilanized magnetic graphene oxide nanosheets (Fe3O4/GrOSi(CH2)3-NH2/H3PMo12O40): A novel magnetically recoverable solid catalyst for H2O2-mediated oxidation of benzylic alcohols under solvent-free conditions
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In this work, 12-molybdophosphoric acid (H3PMo12O40, HPMo) was chemically anchored onto the surface of aminosilanized magnetic graphene oxide (Fe3O4/GrOSi(CH2)3-NH2) and was characterized using different physicochemical techniques, such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), BET specific surface area analysis and magnetic measurements. The results demonstrated the successful loading of HPMo (~31.5 wt%) on the surface of magnetic aminosilanized graphene oxide. XRD patterns, N2 adsorption-desorption isotherms and SEM images confirm the mesostructure of the sample. FT-IR and EDX spectra indicate the presence of the PMo12O403- polyanions in the nanocomposite. The as-prepared Fe3O4/GrOSi(CH2)3-NH2/HPMo nanocomposite has a specific surface area of 76.36 m2 g-1 that is much higher than that of pure HPMo. The selective oxidation of benzyl alcohol to benzaldehyde was initially studied as a benchmark reaction to evaluate the catalytic performance of the Fe3O4/GrOSi(CH2)3-NH2/HPMo catalyst. Then, the oxidation of a variety of substituted primary and secondary activated benzylic alcohols was evaluated with H2O2 under solvent-free conditions. Under the optimized conditions, all alcohols were converted into the corresponding aldehydes and ketones with very high selectivity (≥99%) in moderate to excellent yields (60-96%). The high catalytic performance of the nanocomposite was ascribed to its higher specific surface area and more efficient electron transfer, probably due to the presence of GrO nanosheets. The nanocomposite catalyst is readily recovered from the reaction mixture by a usual magnet and reused at least four times without any observable change in structure and catalytic activity.
- Farhadi, Saeed,Hakimi, Mohammad,Maleki, Mansoureh
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- The selective catalytic oxidation of terminal alcohols: A novel four-component system with MTO as catalyst
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A four-component system (H2O2, MTO, HBr, TEMPO) in acetic acid catalyzes the selective oxidation of terminal alcohols to the corresponding aldehydes with excellent selectivity and yield. The system allows the oxidation of alcohols with hydrogen peroxide as oxidants either selectively to aldehydes or to the corresponding acids, depending on the reaction parameters. The new technique is especially applicable to the oxidation of carbohydrates.
- Herrmann, Wolfgang A.,Zoller, Jochen P.,Fischer, Richard W.
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- Correlation analysis of structure and reactivity in the oxidation of substituted benzyl alcohols by bis(2,2' -bipyridyl) copper(II) permanganate
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The oxidation of substituted benzyl alcohols by bis(2,2'-bipyridyl) copper(II) permanganate (BBCP), leading to the corresponding benzaldehydes is first-order with respect to BBCP. Michaelis-Menten type kinetics were observed with respect to the alcohols. The oxidation of a a-dideuteriobenzyl alcohol indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzyl alcohols were correlated in terms of Charton's triparametric LDR equation whereas ortho-substituted benzyl alcohols were correlated with a four parametric LDRS equation. The results of correlation analyses point to an electron-deficient reaction center in the transition state.
- Vyas,Kothari,Banerji
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- Zinc substituted Keggin-type polyoxometalate on Dowex: a green heterogeneous catalyst for oxidation of alcohols in water
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In this work, homogeneous and heterogeneous oxidation of alcohols by H2O2 in the presence of [(n-C4H9)4?N]5[PW11ZnO39].3H2O and [PW11ZnO39]5? supported on Dowex 22 as catalysts have been investigated. Using water as a green solvent, different alcohols were converted into the corresponding aldehydes and ketones in high to excellent yields. Dowex 22 supported polyoxometalate, PW11Zn@Dowex, was also catalyzed highly robust and selective oxidation of unsaturated alcohols. Leaching and recycling experiments on supported catalyst revealed the excellent stability and reusability of this catalytic system.
- Aghayi, Mehdi,Yadollahi, Bahram,Farsani, Mostafa Riahi
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- Aerobic oxidation of benzyl alcohols to benzaldehydes using monoclinic bismuth vanadate nanoparticles under visible light irradiation: Photocatalysis selectivity and inhibition
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Monoclinic bismuth vanadate nanoparticles (nan-BiVO4) have been used for the selective photo-oxidation of benzyl alcohols (13 examples) to benzaldehydes under visible light irradiation using dioxygen as oxidant. Illumination with a blue LED (λmax = 470 nm) gave yields more than 30 times greater than bulk BiVO4 with >99% selectivity for several cases. Photo-oxidation of PhCH2OH/PhCD2OH isotopomers gave a kinetic isotope effect of 1.3 indicating that C–H bond activation is not the rate determining step in contrast to other reported photocatalysts including TiO2 and carbon nitride. Collectively, structural characterisation, spectroscopic, and reactivity data are correlated with the greater surface area of nan-BiVO4 compared to bulk BiVO4. Furthermore, conversion is shown to be limited as reaction progresses. Control experiments indicate that photo-oxidation is retarded by product aldehyde and that trace amounts (1%) of the corresponding benzoic acid, from over-oxidation, result in significant reduction in conversion.
- Unsworth, Christopher A.,Coulson, Ben,Chechik, Victor,Douthwaite, Richard E.
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Read Online
- Ionic liquid oxidant for efficient and selective oxidation of benzylic alcohols
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Hexamethylenebis (N-methylimidazolium) dichlorochromate was easily prepared by addition of N-methylimidazole to 1,6-dibromohexane to form the corresponding dibromide salt and subsequent treatment with CrO3 in 6 N HCl solution. It is a low-melting orange salt that selectively oxidized benzylic alcohols.
- Hosseinzadeh, Rahman,Mohadjerani, Maryam,Tajbakhsh, Mahmood,Nouzarian, Mahboobe
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Read Online
- Electrochemical Aerobic Oxidative Cleavage of (sp3)C-C(sp3)/H Bonds in Alkylarenes
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An electrochemistry-promoted oxidative cleavage of (sp3)C-C(sp3)/H bonds in alkylarenes was developed. Various aryl alkanes can be smoothly converted into ketones/aldehydes under aerobic conditions using a user-friendly undivided cell setup. The features of air as oxidant, scalability, and mild conditions make them attractive in synthetic organic chemistry.
- Liu, Shuai,Liu, Zhong-Quan,Shen, Tong,Shen, Xu,Wang, Nengyong,Wu, Jintao,Yang, Le,Zhao, Jianyou
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p. 3286 - 3295
(2022/03/14)
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- Preparation method of P-isopropyl benzaldehyde and from isopropylbenzene
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The invention provides a method for preparing p-isopropylbenzaldehyde and from isopropylbenzaldehyde, and the preparation method comprises the following steps of: one step. The method comprises the following steps: adding cumene, an aldehyde solution, dropwise adding hydrochloric acid, heating to 80 - 88 °C after charging, and separating the phase to obtain the organic phase. The method comprises the following steps: uniformly mixing the inorganic base, the water and the phase transfer catalyst into a hydrolysis solution, adding the organic phase obtained in the step, and carrying out phase separation and purification under stirring to obtain p-isopropylbenzyl alcohol. Step III. The method comprises the following steps: adding hydrogen peroxide to isopropyl benzyl alcohol, a catalyst and a phase transfer catalyst obtained in the steps of oxidation and adding hydrogen peroxide, filtering and separating the filtrate to obtain crude aldehyde crude product and purifying to obtain p-propyl benzaldehyde. The preparation method has the advantages of being low in cost, good in process selectivity, mild in process condition and easy to realize industrialization.
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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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- 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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- Efficient Synthesis of Cu(II)-N-Heterocyclic Carbene Complexes in Water and Their Activity Towards Aerobic Alcohol Oxidation
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The majority of the copper N-heterocyclic carbene (NHC) complexes contain Cu in a +1 oxidation state. The Cu(II)-NHC complexes reported so far usually require strict inert atmosphere conditions. In this work, we report a very facile and quantitative preparation of a series of new Cu(II)-NHC complexes (2 a–c) starting from the inexpensive and readily available Cu(II) salts like Cu(OAc)2 and CuCl2 ? 2H2O with imidazolium salts (1 a–c), wherein 2 b and 2 c were exclusively synthesized in water under aerobic condition. It should be emphasized that this is the first example where Cu(II)-NHC complexes have been prepared in the aqueous medium. All the complexes have manifested with a heterobidentate C, O chelate type of coordination to Cu(II) centers forming trans-[Cu(IRpyO)2] (where R=Me, Mes, Dipp) type of complexes where 2 b forms a perfect square planar Cu(II)-NHC complex. Complexes 2 a–c were evaluated as catalysts for the aerobic oxidation of alcohols.
- Ahmad Bhat, Irshad,Avinash, Iruthayaraj,Kumar Sachan, Sharad,Singh, Sadhana,Anantharaman, Ganapathi
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p. 4560 - 4565
(2021/11/13)
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- Visible light mediated selective oxidation of alcohols and oxidative dehydrogenation of N-heterocycles using scalable and reusable La-doped NiWO4nanoparticles
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Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using a scalable and reusable heterogeneous photoredox catalyst in aqueous medium are described. A systematic study led to a selective synthesis of aldehydes under an argon atmosphere while the ODH of partially saturated heterocycles under an oxygen atmosphere resulted in very good to excellent yields. The methodology is atom economical and exhibits excellent tolerance towards various functional groups, and broad substrate scope. Furthermore, a one-pot procedure was developed for the sequential oxidation of benzyl alcohols and heteroaryl carbinols followed by the Pictet-Spengler cyclization and then aromatization to obtain the β-carbolines in high isolated yields. This methodology was found to be suitable for scale up and reusability. To the best of our knowledge, this is the first report on the oxidation of structurally diverse aryl carbinols and ODH of partially saturated N-heterocycles using a recyclable and heterogeneous photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Balasubramaniam, K. K.,Baskar, B.,Divya, P.,Mani Rahulan, K.,Rahman, Abdul,Sridhar, R.,Srinath, S.
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p. 5990 - 6007
(2021/08/24)
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- Aerobic oxidation and oxidative esterification of alcohols through cooperative catalysis under metal-free conditions
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The ABNO@PMO-IL-Br material obtained by anchoring 9-azabicyclo[3.3.1]nonane-3-oneN-oxyl (keto-ABNO) within the mesopores of periodic mesoporous organosilica with bridged imidazolium groups is a robust bifunctional catalyst for the metal-free aerobic oxidation of numerous primary and secondary alcohols under oxygen balloon reaction conditions. The catalyst, furthermore, can be successfully employed in the first metal-free self-esterification of primary aliphatic alcohols affording valued esters.
- Karimi, Babak,Ghahremani, Mina,Vali, Hojatollah,Ciriminna, Rosaria,Pagliaro, Mario
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supporting information
p. 8897 - 8900
(2021/09/10)
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- Radical induced disproportionation of alcohols assisted by iodide under acidic conditions
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The disproportionation of alcohols without an additional reductant and oxidant to simultaneously form alkanes and aldehydes/ketones represents an atom-economical transformation. However, only limited methodologies have been reported, and they suffer from a narrow substrate scope or harsh reaction conditions. Herein, we report that alcohol disproportionation can proceed with high efficiency catalyzed by iodide under acidic conditions. This method exhibits high functional group tolerance including aryl alcohol derivatives with both electron-withdrawing and electron-donating groups, furan ring alcohol derivatives, allyl alcohol derivatives, and dihydric alcohols. Under the optimized reaction conditions, a 49% yield of 5-methyl furfural and a 49% yield of 2,5-diformylfuran were obtained simultaneously from 5-hydroxymethylfurfural. An initial mechanistic study suggested that the hydrogen transfer during this redox disproportionation occurred through the inter-transformation of HI and I2. Radical intermediates were involved during this reaction.
- Huang, Yang,Jiang, Haiwei,Li, Teng,Peng, Yang,Rong, Nianxin,Shi, Hexian,Yang, Weiran
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supporting information
p. 8108 - 8115
(2021/10/29)
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- Synthesis and biological assessment of 4,1-benzothiazepines with neuroprotective activity on the Ca2+ overload for the treatment of neurodegenerative diseases and stroke
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In excitable cells, mitochondria play a key role in the regulation of the cytosolic Ca2+ levels. A dysregulation of the mitochondrial Ca2+ buffering machinery derives in serious pathologies, where neurodegenerative diseases highlight. Since the mitochondrial Na+/Ca2+ exchanger (NCLX) is the principal efflux pathway of Ca2+ to the cytosol, drugs capable of blocking NCLX have been proposed to act as neuroprotectants in neuronal damage scenarios exacerbated by Ca2+ overload. In our search of optimized NCLX blockers with augmented drug-likeness, we herein describe the synthesis and pharmacological characterization of new benzothiazepines analogues to the first-in-class NCLX blocker CGP37157 and its further derivative ITH12575, synthesized by our research group. As a result, we found two new compounds with an increased neuroprotective activity, neuronal Ca2+ regulatory activity and improved drug-likeness and pharmacokinetic properties, such as clog p or brain permeability, measured by PAMPA experiments.
- Arribas, Raquel L.,Braun-Cornejo, María,De Los Ríos, Cristóbal,Estrada-Valencia, Martín,Moreno-Castro, Manuel,Pérez-Marín, Raquel,Rubio-Alarcón, Marcos,Viejo, Lucía
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supporting information
(2021/08/09)
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- Scalable Negishi Coupling between Organozinc Compounds and (Hetero)Aryl Bromides under Aerobic Conditions when using Bulk Water or Deep Eutectic Solvents with no Additional Ligands
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Pd-catalyzed Negishi cross-coupling reactions between organozinc compounds and (hetero)aryl bromides have been reported when using bulk water as the reaction medium in the presence of NaCl or the biodegradable choline chloride/urea eutectic mixture. Both C(sp3)-C(sp2) and C(sp2)-C(sp2) couplings have been found to proceed smoothly, with high chemoselectivity, under mild conditions (room temperature or 60 °C) in air, and in competition with protonolysis. Additional benefits include very short reaction times (20 s), good to excellent yields (up to 98 %), wide substrate scope, and the tolerance of a variety of functional groups. The proposed novel protocol is scalable, and the practicability of the method is further highlighted by an easy recycling of both the catalyst and the eutectic mixture or water.
- Dilauro, Giuseppe,Azzollini, Claudia S.,Vitale, Paola,Salomone, Antonio,Perna, Filippo M.,Capriati, Vito
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supporting information
p. 10632 - 10636
(2021/04/09)
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- PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
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Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
- Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
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- New sustainable synthetic routes to cyclic oxyterpenes using the ecocatalyst toolbox
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Cyclic oxyterpenes are natural products that are mostly used as fragrances, flavours and drugs by the cosmetic, food and pharmaceutical industries. However, only a few cyclic oxyterpenes are accessible via chemical syntheses, which are far from being ecofriendly. We report here the synthesis of six cyclic oxyterpenes derived from ?-pinene while respecting the principles of green and sustainable chemistry. Only natural or biosourced catalysts were used in mild conditions that were optimised for each synthesis. A new generation of ecocatalysts, derived from Mn-rich water lettuce, was prepared via green processes, characterised by MP-AES, XRPD and TEM analyses, and tested in catalysis. The epoxidation of ?-pinene led to the platform molecule, ?-pinene oxide, with a good yield, illustrating the efficacy of the new generation of ecocatalysts. The opening ?-pinene oxide was investigated in green conditions and led to new and regioselective syntheses of myrtenol, 7-hydroxy-α-terpineol and perillyl alcohol. Successive oxidations of perillyl alcohol could be performed using no hazardous oxidant and were controlled using the new generation of ecocatalysts generating perillaldehyde and cuminaldehyde.
- Bihanic, Camille,Grison, Claude,Lasbleiz, Arthur,Le Blainvaux, Pierre,Petit, Eddy,Regnier, Morgan
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- Chemoselective photocatalytic oxidation of alcohols to aldehydes and ketones by nitromethane on titanium dioxide under violet 400 nm LED light irradiation
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In this study, for the first time, nitroalkanes, especially nitromethane, have been used as electron acceptors for the highly chemoselective oxidation of alcohols in the presence of a TiO2 photocatalyst under 400 nm LED irradiation. The reactions showed excellent selectivity for the production of aldehydes. Interestingly, aldehydes such as benzaldehyde and p-methoxybenzaldehyde are stable under the reaction conditions. In the case of the use of 2-nitropropane and 2-methyl-2-nitropropane, the product imine, which is the result of the reaction of the aldehyde with aliphatic amine, is also obtained.
- Kaboudin, Babak,Kazemi, Foad,Rahimi Niaraki, Azam,Saraee, Mohammad Reza
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p. 2326 - 2330
(2020/04/03)
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- Acceptorless and Base-Free Dehydrogenation of Alcohols Mediated by a Dipyridylamine-Iridium(III) Catalyst
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Several dipyridylamine-IrIII and dipyridylamine-RuII complexes have been evaluated in the acceptorless dehydrogenation of alcohols in the absence of base additives. Iridium catalysts were found superior to ruthenium complexes, and the nature of the bridging nitrogen in dipyridylamine ligands was also evidenced as a key parameter. Catalytic reactions were conducted in toluene, but more sustainable solvents such as anisole and p-cymene were found suitable for this transformation.
- Bruneau, Christian,Fischmeister, Cédric,Guo, Liwei,Jayaprakash, Harikrishnan,Wang, Shengdong
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- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
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In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
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supporting information
p. 70 - 79
(2020/06/08)
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- Photocatalytic Molecular Oxygen Activation by Regulating Excitonic Effects in Covalent Organic Frameworks
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Excitonic effects caused by Coulomb interactions between electrons and holes play subtle and significant roles on photocatalysis, yet have been long ignored. Herein, porphyrinic covalent organic frameworks (COFs, specifically DhaTph-M), in the absence or presence of different metals in porphyrin centers, have been shown as ideal models to regulate excitonic effects. Remarkably, the incorporation of Zn2+ in the COF facilitates the conversion of singlet to triplet excitons, whereas the Ni2+ introduction promotes the dissociation of excitons to hot carriers under photoexcitation. Accordingly, the discriminative excitonic behavior of DhaTph-Zn and DhaTph-Ni enables the activation of O2 to 1O2 and O2?-, respectively, under visible light irradiation, resulting in distinctly different activity and selectivity in photocatalytic terpinene oxidation. Benefiting from these results, DhaTph-Ni exhibits excellent photocatalytic activity in O2?-engaged hydroxylation of boronic acid, while DhaTph-Zn possesses superior performance in 1O2-mediated selective oxidation of organic sulfides. This work provides in-depth insights into molecular oxygen activation and opens an avenue to the regulation of excitonic effects based on COFs.
- Qian, Yunyang,Li, Dandan,Han, Yulan,Jiang, Hai-Long
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p. 20763 - 20771
(2020/12/23)
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- Method for directly introducing aldehyde group to aromatic ring
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The invention relates to a method for directly introducing an aldehyde group to an aromatic ring. A purpose of the invention is mainly to solve the problems of low aromatic hydrocarbon conversion rateand low aromatic aldehyde selectivity in the prior art. According to the technical scheme, the method comprises the step of performing a carbonylation reaction on aromatic hydrocarbon and CO under the catalysis of a catalyst to obtain aromatic aldehyde, wherein the catalyst comprises a carrier, an ionic liquid and a compound-state auxiliary agent metal, the carrier is a silicon-based material, the ionic liquid comprises aluminum halide and an imidazole salt represented by a chemical formula I, R1 and R2 are independently selected from C1-C8 alkyl, X is selected from chlorine and bromine, thealuminum halide is represented as AlY3, Y is selected from chlorine and bromine, and the compound-state auxiliary metal comprises at least one selected from Cu, Fe, Cr, V and Mn.
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Paragraph 0098-0100
(2020/05/08)
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- A method for the preparation of aldehydes
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The invention discloses a method for the preparation of ketone, relates to the field of organic synthesis. This invention adopts the organic solvent as a medium, cyclopropene [...] derivative as an active agent, activated DMSO oxidation [...] oxidation. The method of the invention is simple, easy to operate, rapid reaction rate, mild reaction, the reaction rate can be adjusted, more economic, to achieve industrial laid the foundation.
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Paragraph 0092; 0093
(2019/05/28)
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- Aerobic oxidation of alcohols with air catalyzed by decacarbonyldimanganese
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The oxidation of alcohols to carbonyl compounds using air as the terminal oxidant is highly desirable. As described in previous reports, the abstraction of α-H of the alcohol is the most important step, and it typically requires not only a metal catalyst but also complex ligands, co-catalysts and bases. Herein, we report a practical and efficient method for the oxidation of primary alcohols, secondary alcohols, 1,2-diols, 1,2-amino alcohols, and other α-functionalized alcohols using a commercially available catalyst, Mn2(CO)10, and no additives. Preliminary mechanistic studies indicated that an alkoxyl radical intermediate existed in our system, and a plausible mechanism consistent with the experimental results and literature was proposed.
- Meng, Shan-Shui,Lin, Li-Rong,Luo, Xiang,Lv, Hao-Jun,Zhao, Jun-Ling,Chan, Albert S. C.
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supporting information
p. 6187 - 6193
(2019/11/20)
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- Highly efficient and practical aerobic oxidation of alcohols by inorganic-ligand supported copper catalysis
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The oxidation of alcohols to aldehydes or ketones is a highly relevant conversion for the pharmaceutical and fine-chemical industries, and for biomass conversion, and is commonly performed using stoichiometric amounts of highly hazardous oxidants. The aerobic oxidation of alcohols with transition metal complex catalysts previously required complicated organic ligands and/or nitroxyl radicals as co-catalysts. Herein, we report an efficient and eco-friendly method to promote the aerobic oxidation of alcohols using an inorganic-ligand supported copper catalyst 1, (NH4)4[CuMo6O18(OH)6], with O2 (1 atm) as the sole oxidant. Catalyst 1 is synthesized directly from cheap and commonly available (NH4)6Mo7O24·4H2O and CuSO4, which consists of a pure inorganic framework built from a central CuII core supported by six MoVIO6 inorganic scaffolds. The copper catalyst 1 exhibits excellent selectivity and activity towards a wide range of substrates in the catalytic oxidation of alcohols, and can avoid the use of toxic oxidants, nitroxyl radicals, and potentially air/moisture sensitive and complicated organic ligands that are not commercially available. Owing to its robust inorganic framework, catalyst 1 shows good stability and reusability, and the catalytic oxidation of alcohols with catalyst 1 could be readily scaled up to gram scale with little loss of catalytic activity, demonstrating great potential of the inorganic-ligand supported Cu catalysts in catalytic chemical transformations.
- Wei, Zheyu,Ru, Shi,Zhao, Qixin,Yu, Han,Zhang, Gang,Wei, Yongge
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supporting information
p. 4069 - 4075
(2019/08/07)
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- Cyclopropenium-Activated DMSO for Swern-Type Oxidation
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Swern oxidation is widely used to convert alcohols into their corresponding carbonyl compounds. However, the conventional method with use of the volatile oxalyl chloride as an activator requires the reaction to be conducted below -60 °C. We discovered that 3,3-dichloro-1,2-diphenylcyclopropene (DDC) can be used as a new activator for Swern-type oxidations of alcohols, which can be conducted at -20 °C. This new protocol features mild and fast reactions with easy operation. Furthermore, the activator DDC is easy to handle, and diphenylcyclopropenone can be recovered quantitively. This new type of Swern oxidation shows a broad scope of substrates including benzylic, allylic, aliphatic, and biobased alcohols, and gives high yields of up to 93%.
- Guo, Tianfo,Gao, Yu,Li, Zhenjiang,Liu, Jingjing,Guo, Kai
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supporting information
p. 329 - 332
(2019/02/12)
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- Mannich base Cu(II) complexes as biomimetic oxidative catalyst
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Galactose Oxidase (GOase) and catechol oxidase (COase) are the metalloenzymes of copper having monomeric and dimeric sites of coordination, respectively. This paper summarizes the results of our studies on the structural, spectral and catalytic properties of new mononuclear copper (II) complexes [CuL(OAc)] (1), and [CuL2] (2), (HL = 2,4?dichloro?6?{[(2′?dimethyl?aminoethyl)methylamino]methyl}?phenol) which can mimic the functionalities of the metalloenzymes GOase and COase. The structure of the compounds has been elucidated by X-ray crystallography and the mimicked Cu(II) catalysts were further characterized by EPR. These mimicked models were used for GOase and COase catalysis. The GOase catalytic results were identified by GC–MS and, analyzed by HPLC at room temperature. The conversion of benzyl alcohol to benzaldehyde were significant in presence of a strong base, Bu4NOMe in comparison to the neutral medium. Apart from that, despite of being monomeric in nature, both the homogeneous catalysts are very prone to participate in COase mimicking oxidation reaction. Nevertheless, during COase catalysis, complex 1 was found to convert 3,5?ditertarybutyl catechol (3,5-DTBC) to 3,5?ditertarybutyl quinone (3,5-DTBQ) having greater rate constant, kcat or turn over number (TON) value over complex 2. The generation of reactive intermediates during COase catalysis were accounted by electrospray ionization mass spectrometry (ESI-MS). Through mechanistic approach, we found that H2O2 is the byproduct for both the GOase and COase catalysis, thus, confirming the generation of reactive oxygen species during catalysis. Notably, complex 1 having mono-ligand coordinating atmosphere has superior catalytic activity for both cases in comparison to complex 2, that is having di-ligand environment.
- Kundu, Bidyut Kumar,Ranjan, Rishi,Mukherjee, Attreyee,Mobin, Shaikh M.,Mukhopadhyay, Suman
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p. 164 - 173
(2019/04/10)
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- Method for preparing aromatic aldehyde
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The invention relates to a method for preparing aromatic aldehyde. The invention mainly aims to solve the problems of low conversion rate of aromatic hydrocarbon and low yield of aromatic aldehyde inthe prior art. The method comprises a step of subjecting aromatic hydrocarbon and CO to a carbonylation reaction under the catalysis of a catalyst so as to obtain aromatic aldehyde, wherein the catalyst comprises ionic liquid, a compound active metal and a compound auxiliary metal, the ionic liquid is quaternary ammonium salt type ionic liquid, the compound active metal comprises Zr, and the compound auxiliary metal comprises Ru. With such a technical scheme, the above technical problems are well solved, and the method can be used for industrial production of aromatic aldehyde.
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Paragraph 0110-0112; 0121
(2019/12/25)
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- Nitrogen Dioxide Catalyzed Aerobic Oxidative Cleavage of C(OH)–C Bonds of Secondary Alcohols to Produce Acids
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Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation, and separation procedures. Herein, NO2 in DMSO is shown to effectively catalyze the aerobic oxidative cleavage of C(OH)?C bonds to form a carboxylic group, and NO2 was generated in situ by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted into acids in excellent yields in this transition-metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail studies revealed that NO2 from nitrates promoted the reaction, and NO2 served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.
- Liu, Mingyang,Zhang, Zhanrong,Song, Jinliang,Liu, Shuaishuai,Liu, Huizhen,Han, Buxing
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p. 17393 - 17398
(2019/11/11)
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- Synthetic alkyl aromatic aldehyde (by machine translation)
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The invention relates to synthetic alkyl aromatic aldehyde. To solve the problems in the prior art and the location of the alkyl aromatic hydrocarbon conversion of alkyl aromatic aldehyde the problem of low selectivity, the invention adopts the method of synthetic alkyl aromatic aldehyde, included in the catalyst under the catalysis of the alkyl aromatic hydrocarbon to CO carbonylation reaction to obtain the alkyl aromatic aldehyde, wherein said catalyst comprises a rare earth perfluoroalkyl sulfonate and the accelerator and the technical scheme, better solved this technical problem, can be used in the industrial production of alkyl aromatic aldehyde. (by machine translation)
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Paragraph 0093-0095; 0100; 0101
(2019/04/30)
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- Method for synthesizing alkyl aromatic aldehydes by carbonylating alkyl aromatic hydrocarbons
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The invention relates to a method for synthesizing alkyl aromatic aldehydes by carbonylating alkyl aromatic hydrocarbons. The problems of low conversion rate of alkyl aromatic hydrocarbons and low selectivity of para-alkyl aromatic aldehydes in the prior art are mainly solved. The method for synthesizing alkyl aromatic aldehydes by carbonylating alkyl aromatic hydrocarbons is characterized in thatthe alkyl aromatic hydrocarbons and CO undergo a carbonylation reaction under the catalysis of a catalyst in order to obtain the alkyl aromatic aldehydes, wherein the catalyst includes a halogenatedalkylimidazolium salt and rare earth perfluoroalkyl sulfonate. The method well solves the problems, and can be used in the industrial production of the alkyl aromatic aldehydes.
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Paragraph 0104-0106; 0111
(2019/04/30)
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- Method for synthesizing alkyl aromatic aldehydes
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The invention relates to a method for synthesizing alkyl aromatic aldehydes. The problems of low conversion rate of alkyl aromatic hydrocarbons and low selectivity of para-alkyl aromatic aldehydes inthe prior art are mainly solved. The method for synthesizing the alkyl aromatic aldehydes is characterized in that the alkyl aromatic hydrocarbons and CO undergo a carbonylation reaction under the catalysis of a catalyst in order to obtain the alkyl aromatic aldehydes, wherein the catalyst includes a halogenated alkylimidazolium salt, aluminum halide and an accelerator. The method well solves theproblems, and can be used in the industrial production of the alkyl aromatic aldehydes.
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Paragraph 0105-0107; 0112
(2019/04/30)
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- Stepwise degradation of hydroxyl compounds to aldehydes: Via successive C-C bond cleavage
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Stepwise degradation of hydroxyl compounds to aldehydes via successive cleavage of C-C bonds was achieved by using a bimetallic catalytic system (PdCl2 + CuCl) without any ligands and additives. The broad applicability is expanded to a diverse range of aromatic, aliphatic, primary and secondary alcohols, as well as lignin model compounds.
- Liu, Mingyang,Zhang, Zhanrong,Shen, Xiaojun,Liu, Huizhen,Zhang, Pei,Chen, Bingfeng,Han, Buxing
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p. 925 - 928
(2019/01/24)
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- Visible light-catalytic dehydrogenation of benzylic alcohols to carbonyl compounds by using an eosin y and nickel-thiolate complex dual catalyst system
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We developed a simple and environmentally benign visible-light-driven dehydrogenation of benzylic alcohols to the corresponding aldehydes or ketones. By using the dual catalyst system consisting of eosin Y as a photocatalyst and a Ni(ii) complex as a proton reduction catalyst, we could dehydrogenate benzylic alcohols to aldehydes or ketones with excellent yields under mild conditions. The sole byproduct is hydrogen gas.
- Yang, Xiu-Jie,Zheng, Li-Qiang,Wu, Li-Zhu,Tung, Chen-Ho,Chen, Bin
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supporting information
p. 1401 - 1405
(2019/03/26)
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- New thiosemicarbazide and dithiocarbazate based oxidovanadium(iv) and dioxidovanadium(v) complexes. Reactivity and catalytic potential
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The Schiff bases {H3dfmp-(smdt)2} (I), {H3dfmp-(sbdt)2} (II) and {H3dfmp-(tsc)2} (III) are synthesized by reaction of 2,6-diformyl-4-methylphenol (H3dfmp) and S-methyldithiocarbazate (smdt), S-benzyldithiocarbazate (sbdt) and thiosemicarbazide (tsc), respectively. Addition of [VIVO(acac)2] to solutions of these compounds in methanol leads to the formation of the oxidovanadium(iv) complexes [VIVO{Hdfmp-(smdt)2(CH3OH)}] (1), [VIVO{Hdfmp-(sbdt)2(CH3OH)}] (2) and [VIVO{Hdfmp-(tsc)2(CH3OH)}] (3). All these VIVO-compounds can be oxidized to the corresponding dioxidovanadium(v) (VVO2) complexes in methanolic solution upon aerial oxidation in the presence of KOH. The isolated compounds are K[VVO2{Hdfmp-(smdt)2}] (4), K[VVO2{Hdfmp-(sbdt)2}] (5) and K[VVO2{Hdfmp-(tsc)2}] (6). The Cs+ salts of these complexes i.e. Cs[VVO2{Hdfmp-(smdt)2}] (7), Cs[VVO2{Hdfmp-(sbdt)2}] (8) and Cs[VVO2{Hdfmp-(tsc)2}] (9) are prepared similarly in the presence of CsOH. All these compounds are characterized by various spectroscopic techniques like FT-IR, UV-visible, and 1H and 51V NMR and thermal studies. IR spectral data confirm the coordination of ligands through the azomethine nitrogen, the sulphur and the phenolic oxygen atoms to the metal. These complexes show excellent catalytic activity and selectivity for the oxidation of benzyl alcohol and ethylbenzene in the presence of H2O2 as an oxidant. Various parameters such as the amount of catalyst and oxidant, reaction time, reaction temperature and solvent were taken into consideration to optimize these catalytic oxidations. Compound 7 was also remarkably efficient and selective in the catalytic oxidation of primary and secondary alcohols to the corresponding aldehyde/ketone, as well as of several aromatic compounds such as toluene, benzene, cumene and tetralin.
- Maurya, Mannar R.,Sarkar, Bithika,Kumar, Amit,Ribeiro, Nádia,Miliute, Aistè,Pessoa, Jo?o Costa
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p. 17620 - 17635
(2019/11/25)
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- Visible-Light-Driven Photocatalytic Oxidation of Organic Chlorides Using Air and an Inorganic-Ligand Supported Nickel-Catalyst Without Photosensitizers
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Engineering photoredox-triggered chemical transformation via visible light has been an emerging area in organic synthesis. However, most of the well-established photocatalysts are based upon either transition metal complexes involved with noble metals and organic ligands or photosensitive organic dyes, the development of pure inorganic molecular photocatalysts that could provide better stability and durability is greatly retarded. Herein we discover that the Anderson polyoxometalate (POM) Na4[NiMo6O18(OH)6] (1), which consists of pure inorganic framework built from a central NiII core supported by six MoVIO6 inorganic scaffold/ligands, can be used as a powerful photocatalyst. Upon irradiation with visible light (>400 nm), the compound can catalyze, in high efficiency, a wide range of reactions, including the oxidative cross-coupling reaction of chlorides with amines, as well as oxidation of chlorides using molecular oxygen, affording various imines, aldehydes, and ketones, respectively in high selectivity and good yields. Owing to the robust inorganic framework, this catalyst exhibits excellent stability during the catalysis and reusability with little loss of the catalytic activity, thus providing an alternative without use of complicated organic ligands and expensive noble metal-based photosensitizers.
- Yu, Han,Wang, Jingjing,Zhai, Yongyan,Zhang, Mengqi,Ru, Shi,Han, Sheng,Wei, Yongge
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p. 4274 - 4279
(2018/09/10)
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- Selective aerobic oxidation of halides and amines with an inorganic-ligand supported zinc catalyst
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A practical, efficient and environmentally benign catalytic protocol for the oxidative cross-coupling reaction of halides with amines, oxidative self-coupling of amines and oxidation of halides was developed with inorganic-ligand supported ZnPOM (NH4)4[ZnMo6O18(OH)6] using molecular oxygen. This method mainly utilizes an inorganic polymolybdate ligand to support the Zn2+ ion, avoiding the use of complicated organic ligands.
- Wang, Jingjing,Zhai, Yongyan,Wang, Ying,Yu, Han,Zhao, Wenshu,Wei, Yongge
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supporting information
p. 13323 - 13327
(2018/10/15)
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- Cu(II) Schiff base complex supported on Fe3O4 nanoparticles as an efficient nanocatalyst for the selective aerobic oxidation of alcohols
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Herein, we have prepared a new Cu(II) Schiff base complex supported onto the surface of modified Fe3O4 nanoparticles as highly stable, heterogeneous and magnetically recyclable nanocatalyst for the selective aerobic oxidation of different alcohols. The structure, morphology, chemical composition and magnetic property of the nanocatalyst and its precursors were characterized using FT-IR, TGA, AAS, ICP-AES, XRD, SEM, EDS, VSM and N2 adsorption–desorption analyses. Characterization results exhibited the uniform spherical morphology for nanocatalyst and its precursors. A promising eco-friendly method with short reaction time and high conversion and selectivity for oxidation of various primary and secondary alcohols under O2 atmosphere condition was achieved. The synthesized nanocatalyst could be recovered easily by applying an external magnetic field and reused for least eight subsequent reaction cycles with only negligible deterioration in catalytic performance.
- Aghajani, Milad,Monadi, Niaz
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- Sulfuric Acid-Promoted Oxidation of Benzylic Alcohols to Aromatic Aldehydes in Dimethyl Sulfoxide: An Efficient Metal-Free Oxidation Approach
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An efficient metal-free oxidation of benzylic alcohols to Aaromatic aldehydes is described. Heating a solution of the benzylic alcohol in DMSO in the presence of H 2 SO 4 afforded the corresponding aldehyde in excellent yield. This oxidation reaction, which proceeds with a short reaction time and no side products, is akin to the Pfitzner-Moffatt oxidation, but without the need for N, N ′-dicyclohexylcarbodiimide.
- Sheikhi, Ehsan,Adib, Mehdi,Karajabad, Morteza Akherati,Gohari, Seyed Jamal Addin
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p. 974 - 978
(2018/04/23)
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- Highly practical and efficient preparation of aldehydes and ketones from aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst
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Herein, we divulge an efficient protocol for aerobic oxidation of alcohols with an inorganic-ligand supported iodine catalyst, (NH4)5[IMo6O24]. The catalyst system is compatible with a wide range of groups and exhibits high selectivity, and shows excellent stability and reusability, thus serving as a potentially greener alternative to the classical transformations.
- Zhang, Mengqi,Zhai, Yongyan,Ru, Shi,Zang, Dejin,Han, Sheng,Yu, Han,Wei, Yongge
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supporting information
p. 10164 - 10167
(2018/09/13)
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- Magnetic crosslinked copoly(ionic liquid) nanohydrogel supported palladium nanoparticles as efficient catalysts for the selective aerobic oxidation of alcohols
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Nowadays it is still a great sustainable processes challenge to produce efficient, selective and easy magnetic recovery and recycling catalysts for oxidation of alcohols using air as the oxidant. In this work, a new magnetic nanohydrogel comprising [DABCO-allyl][Br] ionic liquid, allyl alcohol and N,N’-methylenebis(acrylamide) is used for stabilization of small and highly uniform palladium nanoparticles of 3–4 nm size MXCPILNHG@Pd. This material has been characterized by Fourier-transform infrared spectroscopy (FTIR), atomic adsorption spectroscopy (AAS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), SEM-Map, energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectra (XPS), vibrating-sample magnetometer (VSM) and dynamic light scattering (DLS). According to optimization of cross-linking degree and ratio of DABCO-IL, MXCPILNHG-2@Pd is found as a highly selective catalyst in oxidations of primary alcohols to the corresponding aldehydes in toluene and to acids in water. Furthermore, secondary alcohols were reacted efficiently to the corresponding ketones in both toluene and water. Catalyst is magnetically recovered and recycled for several times in both toluene and water and the reused catalysts are characterized by TEM and XPS.
- Gholinejad, Mohammad,Afrasi, Mahmoud,Nikfarjam, Nasser,Nájera, Carmen
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p. 185 - 195
(2018/07/14)
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- Photocatalytic Properties and Mechanistic Insights into Visible Light-Promoted Aerobic Oxidation of Sulfides to Sulfoxides via Tin Porphyrin-Based Porous Aromatic Frameworks
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Using concepts of biomimetic catalysis, a kind of tin porphyrin-based porous aromatic framework (SnPor@ PAF) with broad and strong optical absorption in the visible light region was successfully synthesized and subsequently used in the aerobic oxidation of sulfides to sulfoxides under ambient conditions and visible light irradiation, in which exhibited enzyme-like features of high efficiency and high selectivity. More interestingly, heterogeneous SnPor@PAF was naturally regarded as an intriguing and versatile photosensitizer for photocatalytic transformation and could be reused several times because of its robust and rigid porphyrin framework. As expected, their π-conjugated structure characteristic in the molecular skeleton might facilitate the activation of molecular oxygen under mild reaction conditions and promoted the production of reactive oxygen species (singlet oxygen (1O2) and superoxide radical anion (O2.?)), which would involve energy transfer and/or electron transfer process. Experimental investigations including emission quenching experiment, oxygen-isotope labelling, typical inhibition experiments, classical fluorescence probe study, photo-oxidation of α-terpinene and in situ electron spin resonance, could provide a mechanistic insight into the photocatalytic reactions. (Figure presented.).
- Jiang, Jun,Luo, Rongchang,Zhou, Xiantai,Chen, Yaju,Ji, Hongbing
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supporting information
p. 4402 - 4411
(2018/10/15)
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- Cobalt Vanadium Oxide Supported on Reduced Graphene Oxide for the Oxidation of Styrene Derivatives to Aldehydes with Hydrogen Peroxide as Oxidant
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Cobalt vanadium oxide supported on reduced graphene oxide showed excellent performance in the oxidation of styrene derivatives to the corresponding aldehydes with hydrogen peroxide as oxidant. An electron-donating group at the para -position of the aromatic ring facilitates the formation of the corresponding aldehyde. Compared with conventional methods, the newly designed heterogeneous catalytic system offers a promising prospect because of its economic applicability and environmental friendliness.
- Zou, Hui,Hu, Chuanfeng,Chen, Kaihao,Xiao, Guansheng,Peng, Xinhua
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supporting information
p. 2181 - 2184
(2018/10/02)
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- Polyoxometalate-based metal-organic frameworks for selective oxidation of aryl alkenes to aldehydes
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Polyoxometalates (POMs) show considerable catalytic performance toward the selective oxidation of alkenes to aldehydes, which is commercially valuable for the production of pharmaceuticals, dyes, perfumes, and fine chemicals. However, the low specific surface area of POMs as heterogeneous catalysts and poor recyclability as homogeneous catalysts have hindered their wide application. Dispersing POMs into metal-organic frameworks (MOFs) for the construction of POM-based MOFs (POMOFs) suggests a promising strategy to realize the homogeneity of heterogeneous catalysis. Herein, we report two new POMOFs with chemical formulas of [Co(BBTZ)2][H3BW12O40]·10H2O (1) and [Co3(H2O)6(BBTZ)4][BW12O40]·NO3·4H2O (2) (BBTZ = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene) for the selective oxidation of alkenes to aldehydes. Compound 1 possesses a non-interpenetrated three-dimensional (3D) cds-type open framework with a 3D channel system. Compound 2 displays a 3D polyrotaxane framework with one-dimensional channels along the [100] direction. In the selective oxidation of styrene into benzaldehyde, compound 1 can achieve a 100% conversion in 4 h with 96% selectivity toward benzaldehyde, which is superior to that of compound 2. A series of control experiments reveal that the co-role of [BW12O40]5- and Co2+ active center as well as a more open framework feature co-promote the catalytic property of the POMOFs in this case. This work may suggest a new option for the development of POMOF catalysts in the selective oxidation of alkenes.
- Ma, Yuanyuan,Peng, Haiyue,Liu, Jianing,Wang, Yonghui,Hao, Xiuli,Feng, Xiaojia,Khan, Shifa Ullah,Tan, Huaqiao,Li, Yangguang
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p. 4109 - 4116
(2018/04/10)
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- Selective endoperoxide formation by heterogeneous TiO2 photocatalysis with dioxygen
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We report the selective formation of endoperoxides by aerobic TiO2 photocatalysis through the cyclic addition of dioxygen and a non-conjugated diene, the first heterogeneous catalytic system for endoperoxide synthesis. This green protocol does not require any additive and the photocatalyst is abundant and recyclable, providing a yield up to 64% and >20:1 diastereoselectivity. Mechanistic investigations were carried out by using product analysis, kinetic studies, O-18 labelling experiments, electron-spin resonance and a set of quenching experiments. Superoxide (but not singlet oxygen, triplet oxygen or peroxide) is directly involved in the reaction cascade to form the endoperoxide product. The new findings may be helpful for future for designing eco-friendly and energy sustainable strategies for selective oxygenation reactions using semiconductors, O2 and sunlight.
- Qiao, Xiaofeng,Biswas, Subharanjan,Wu, Wenli,Zhu, Feng,Tung, Chen-Ho,Wang, Yifeng
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supporting information
p. 2421 - 2427
(2018/04/11)
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