- Synthesis, characterization and catalytic performance of a Fe polyoxometalate/silica composite in the oxidation of alcohols with hydrogen peroxide
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Fe(III) substituted Keggin type polyoxometalate in amorphous silica matrix, (n-C4H9)4N)4[PW 11FeO39]/SiO2 (PWFe/SiO2), has been synthesized by sol-gel method. The synthesized PWFe/SiO2 composite was characterized by various analytical and spectroscopic techniques. Results indicated that the primary Keggin structure remain after incorporation in silica matrix. As a heterogeneous catalyst, PWFe/SiO2 composite showed an elevated catalytic activity and selectivity with high to excellent yields for oxidation of alcohols into aldehydes by H2O2. The stability and reusability of the catalyst was very high, so these composites are suitable for the heterogeneous catalysis by hydrogen peroxide.
- Farsani, Mostafa Riahi,Yadollahi, Bahram
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- The superiority of cuprous chloride to iodide in the selective aerobic oxidation of benzylic alcohols at ambient temperature
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Cuprous halides, best described as (CuX)n (X = Cl?, Br?, and I?) in their solid state, catalyse selective aerobic oxidation of alcohols with the assistance of both NMI (N-methylimidazole) and TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl), and the iodide generally demonstrates the highest activity, for example, in the oxidation of 1-octanol at ambient temperature under 24 h' reaction. However, in the aerobic oxidation of benzylic alcohols, the chloride showed superiority to the iodide in that the aerobic oxidation was quantitatively completed within 3 h at ambient temperature whereas the iodide showed only about half the activity of the chloride analogue. By probing the system using electrochemistry, electric conductivity, and 1H NMR titration, it was revealed that the surprising anomaly was due to the difference in the rate of forming active species, [Cu (NMI)2X(MeCN)], from the polymeric solid in a two-stage process. Substrates expansion of 11 benzylic alcohols indicated that CuCl/NMI/TEMPO system demonstrated quantitative conversion of benzylic alcohols into corresponding aldehydes within 3 h and showed great tolerance to the substituents on the phenyl ring of the substrates. Furthermore, electron-withdrawing substituent was beneficial to the oxidation and could offset the steric effect at orthro-substituent. Such a behaviour suggested that in the catalysis, increasing the acidity of the hydroxyl group (OH) of the substrates could ease the oxidation, which implied that the deprotonation via an internal pathway might be one of the rate-determining steps. Our results also showed that the anion halide participated actively in the catalysis by coordinating to Cu(I) in the active species.
- Ma, Ruonan,Xiao, Zhiyin,Zhong, Wei,Lu, Chunxin,Shen, Zhongquan,Zhao, Dan,Liu, Xiaoming
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- Oxidation of Substituted Benzyl Alcohols by Quinoxalinium Dichromate. A Kinetic Study
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Quinoxalinium dichromate (QxDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl sulfoxide (DMSO) and in the presence of acid to the corresponding aldehydes. The reaction has unit dependence on each of the alcohol, QxDC, and acid concentrations. Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship. The reaction constant ρ was -1.09 +/- 0.01 at 303 K. Oxidation of α,α-dideuteriobenzyl alcohol indicated the presence of a substantial primary kinetic isotope effect (kH/kD = 6.78 at 303 K). The reaction failed to induce the polymerization of acrylonitrile. The rates of oxidation were determined at different temperatures and the activation parameters were evaluated. The analysis of the dependence of the kinetic isotope effect on temperature indicated that the reaction involves a symmetrical cyclic transition state. A suitable mechanism is proposed.
- Oezguen, Beytiye,Degirmenbasi, Nebahat
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- Use of sodium bromate for aromatic bromination: Research and development
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Sodium bromate is a powerful brominating agent for aromatic compounds that contain deactivating substituents. A bromination process, in which sodium bromate was utilized, was optimized on laboratory scale. Addition of a strong acid into a stirred aqueous solution, or slurry, of the substrate and bromate salt at 40-100°C, leads to the decomposition of the bromate ions and production of the active brominating species. Substrates such as nitrobenzene, benzoic acid, and benzaldehyde were brominated in high yields (85-98%) and specificity. The reaction is especially useful for the bromination of disubstituted benzenes, such as 4-nitrofluorobenzene or 4-fluorobenzoic acid. Several substrates, such as dinitrobenzenes or nitrobenzoic acids, did not undergo bromination at all. The main parameters of the reaction and some of its synthetic potential are discussed.
- Groweiss, Amiram
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- Solvent free aerobic oxidation of alcohols with 1-methyl-2-azaadamantane N-oxyl as a recyclable catalyst through phase separation
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An expedient, non-metallic green protocol for aerobic oxidation of alcohols was established. 1-Methyl-2-azaadamantane N-oxyl was used as the core catalyst due to its superior chemical stability and catalytic performance. The catalyst can be easily reused through phase separation by taking advantage of its solubility feature, which varies with its oxidation state.
- Kuang, Yongbo,Nabae, Yuta,Hayakawa, Teruaki,Kakimoto, Masa-Aki
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- Efficient and selective oxidation of alcohols in water employing palladium supported nanomagnetic Fe3O4@hyperbranched polyethylenimine (Fe3O4@HPEI.Pd) as a new organic–inorganic hybrid nanocatalyst
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Palladium immobilized magnetic nanoFe3O4@hyperbranched polyethylenimine (Fe3O4@HPEI.Pd) was prepared according to a simple and cost effective pathway and it was employed as a new efficient and selective organic–inorganic hybrid nanocatalyst for the aqueous oxidation of primary and secondary alcohols to their corresponding products in good yields applying oxone (potassium hydrogen monopersulfate) and H2O2 as an oxidant at room temperature. Moreover, the catalytic system was reused at least 13 times without significant loss of activity. The complete characterization of this efficient nanocatalyst was investigated by FTIR, UV–Vis, TEM, SEM, XRD, TGA, VSM, ICP and EDX techniques.
- Ramazani, Ali,Khoobi, Mehdi,Sadri, Fariba,Tarasi, Roghayeh,Shafiee, Abbas,Aghahosseini, Hamideh,Joo, Sang Woo
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- SBA-15-functionalized TEMPO confined ionic liquid: An efficient catalyst system for transition-metal-free aerobic oxidation of alcohols with improved selectivity
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A novel SBA-15-functionalized TEMPO confined ionic liquid [BMIm]Br was found to be a highly efficient and recyclable catalyst system for the transition-metal-free aerobic oxidation of a wide range of structurally diverse alcohols. Thanks to the strong physical confinement of the ionic liquid inside the mesochannels of SBA-15-supported TEMPO, the resulting solid catalyst showed improved selectivity in the aerobic oxidation of allylic alcohols. The catalyst can be recovered and re-used for at least 11 reaction runs without significant loss of either activity or confined IL.
- Karimi, Babak,Badreh, Ebrahim
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- Magnetic copper ferrite nanoparticles/TEMPO catalyzed selective oxidation of activated alcohols to aldehydes under ligand- and base-free conditions in water
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A novel, effective and sustainable strategy for the synthesis of aldehydes has been developed using inexpensive, readily available, oxygen-stable and recyclable CuFe2O4 nanoparticles as the catalyst. The corresponding substituted aldehydes were obtained in moderate to good yields by aerobic oxidation of aromatic alcohols in water under dioxygen atmosphere. Importantly, a ligand or a base was not necessary. The catalyst was completely recoverable with an external magnet and could be reused six times without significant loss of catalytic activity.
- Zhu, Xiao,Yang, Daoshan,Wei, Wei,Jiang, Min,Li, Lulu,Zhu, Xiangbing,You, Jinmao,Wang, Hua
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- A green approach for aerobic oxidation of benzylic alcohols catalysed by CuI-Y zeolite/TEMPO in ethanol without additional additives
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An efficient and green protocol for aerobic oxidation of benzylic alcohols in ethanol using CuI-Y zeolite catalysts assisted by TEMPO (TEMPO = 2,2,6,6-tetramethyl-1-piperidine-N-oxyl) as the radical co-catalyst in the presence of atmospheric air under mild conditions is reported. The CuI-Y zeolite prepared via ion exchange between CuCl and HY zeolite was fully characterized by a variety of spectroscopic techniques including XRD, XPS, SEM, EDX and HRTEM. The incorporation of Cu(i) into the 3D-framework of the zeolite rendered the catalyst with good durability. The results of repetitive runs revealed that in the first three runs, there was hardly a decline in activity and a more substantial decrease in yield was observed afterwards, while the selectivity remained almost unchanged. The loss in activity was attributed to both the formation of CuO and the bleaching of copper into the liquid phase during the catalysis, of which the formation of CuO was believed to be the major contributor since the bleaching loss for each run was negligible (2%). In this catalytic system, except TEMPO, no other additives were needed, either a base or a ligand, which was essential in some reported catalytic systems for the oxidation of alcohols. The aerobic oxidation proceeded under mild conditions (60 °C, and 18 hours) to quantitatively and selectively convert a wide range of benzylic alcohols to corresponding aldehydes, which shows great potential in developing green and environmentally benign catalysts for aerobic oxidation of alcohols. The system demonstrated excellent tolerance against electron-withdrawing groups on the phenyl ring of the alcohols and showed sensitivity to steric hindrance of the substrates, which is due to the confinement of the pores of the zeolite in which the oxidation occurred. Based on the mechanism reported in the literature for homogenous oxidation, a mechanism was analogously proposed for the aerobic oxidation of benzylic alcohols catalysed by this Cu(i)-containing zeolite catalyst. This journal is
- Senthilkumar, Samuthirarajan,Zhong, Wei,Natarajan, Mookan,Lu, Chunxin,Xu, Binyu,Liu, Xiaoming
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- Kinetics of Oxidation of Substituted Benzyl Alcohols by Quinolinium Dichromate
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Quinolinium dichromate (QDC) oxidizes benzyl alcohol and substituted benzyl alcohols smoothly in dimethyl formamide, in the presence of acid.The reaction has unit dependence on each of the alcohol, QDC, and acid concentrations.Electron-releasing substituents accelerate the reaction, whereas electron-withdrawing groups retard the reaction, and the rate data obey Hammett's relationship.The reaction constant ρ was -1.67 +/- 0.08 at 313 K.The kinetic isotope effect, kH/kD, was 5.89 at 313 K.The reaction does not induce polymerization of acrylonitrile.The observed experimental data have been rationalized in terms of a hydride ion transfer in the rate-determining step.
- Dey, Doyamoy,Mahanti, Mahendra K.
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- Heterogeneous oxidation of alcohols with hydrogen peroxide catalyzed by polyoxometalate metal–organic framework
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HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were synthesized and characterized by elemental analysis, UV–Vis, FT-IR, cyclic voltammetry and XRD. These compounds were used as catalyst for the selective oxidation of alcohols by hydrogen peroxide. Within them, PW-MOF showed a higher catalytic activity compared to other catalysts in a similar reaction condition. Therefore, PW-MOF catalyst system was successfully used for the selective oxidation of the benzylic, linear and secondary alcohols to the corresponding aldehydes and ketones. Also, allylic alcohols were converted to the corresponding aldehydes with high conversion and significant selectivity. Moreover, PW-MOF was stable to leaching, behaved as true heterogeneous catalysts, easily recovered by filtration, and reused four times with the preserve of the catalytic performance.
- Babahydari, Ali Kazemi,Fareghi-Alamdari, Reza,Hafshejani, Shahrbanou Moradpour,Rudbari, Hadi Amiri,Farsani, Mostafa Riahi
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- Lead-free perovskite Cs3Bi2Br9 heterojunctions for highly efficient and selective photocatalysis under mild conditions
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Lead halide perovskites possess excellent photoelectric properties and are promising for photocatalysis. However, the toxicity of lead in these perovskites has hindered their application. We designed a stable, lead-free heterojunction to enhance the photocatalytic efficiency of the perovskite. A production rate of 1465 μmol/g/h for the selective oxidation of benzyl alcohol was achieved, which was the highest among all inorganic catalysts without zero-valent metal cocatalyst in the atmosphere at room temperature. In addition, the heterojunction degraded 74.7% of 10 ppm 2-mercaptobenzothiazole within 10 min, and achieving a final degradation rate exceeding 99.9% in 20 min, which is the best degradation efficiency among all reported studies. Detailed optical characterisation proved that the high efficiency stems from band matching and charge transfer between Cs3Bi2Br9 and TiO2. This result will inspire the design of additional lead-free perovskites for photocatalysis.
- He, Jing-Hui,Li, Lanxin,Lu, Jian-Mei,Sun, Qimeng,Wang, Jia,Wei, Jialiang,Ye, Wen
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- Controlled reduction of activated primary and secondary amides into aldehydes with diisobutylaluminum hydride
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A practical method is disclosed for the reduction of activated primary and secondary amides into aldehydes using diisobutylaluminum hydride (DIBAL-H) in toluene. A wide range of aryl and alkyl N-Boc, N,N-diBoc and N-tosyl amides were converted into the corresponding aldehydes in good to excellent yields. Reduction susceptible functional groups such as nitro, cyano, alkene and alkyne groups were found to be stable. Broad substrate scope, functional group compatibility and quick conversions are the salient features of this methodology.
- Azeez, Sadaf,Kandasamy, Jeyakumar,Sabiah, Shahulhameed,Sureshbabu, Popuri
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supporting information
p. 2048 - 2053
(2022/03/31)
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- DIBALH: From known fundamental to an unusual reaction; Chemoselective partial reduction of tertiary amides in the presence of esters
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This study presents a quick and reliable approach to the chemoselective partial reduction of tertiary amides to aldehydes in the presence of readily reducible ester groups using commercial DIBALH reagent. Moreover, the developed method was also extended to multi-functional molecules bearing ester moieties, which were successfully chemoselectively reduced to the corresponding aldehydes. This journal is
- An, Duk Keun,Heo, Yu Jin,Jaladi, Ashok Kumar,Kim, Hyun Tae
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p. 33809 - 33813
(2021/12/09)
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- Preparation method of m-phenoxy benzaldehyde
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The invention provides a preparation method of m-phenoxy benzaldehyde, and belongs to the technical field of synthesis of medical intermediates. The preparation method comprises the following steps: mixing m-cresol, halogenated benzene, inorganic base and a catalyst for condensation reaction to obtain m-phenoxy toluene; mixing the m-phenoxy toluene with an oxidant, and carrying out an oxidation reaction under acidic conditions to obtain m-phenoxy benzaldehyde. According to the preparation method, m-cresol and halogenated benzene are taken as raw materials, the cost of the raw materials is low, m-phenoxy toluene is firstly prepared through a condensation reaction, then m-phenoxy toluene is oxidized into m-phenoxy benzaldehyde, the yield of the product is high, and the preparation is simple. The result of the embodiment shows that the yield of the m-phenoxybenzaldehyde prepared by the method is 56.8% or above.
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Paragraph 0074-0075
(2021/04/17)
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- Preparation method of m-phenoxy benzaldehyde
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The invention belongs to the technical field of organic synthesis, and particularly relates to a preparation method of m-phenoxy benzaldehyde. According to the preparation method provided by the invention, m-hydroxybenzaldehyde is salified by phenolic hydroxyl under an alkaline anhydrous condition, and then is subjected to substitution reaction with halobenzene to obtain m-phenoxy benzaldehyde, so that disproportionation reaction of aldehyde groups during reaction in an alkaline aqueous solution is avoided, the utilization rate of raw materials is increased, and side reactions are reduced. The purification of the m-phenoxybenzaldehyde product and the improvement of the yield are facilitated. The test result of the embodiment shows that the yield of m-phenoxybenzaldehyde obtained by the preparation method provided by the invention is 79.9-81%, and the yield is high; the gas phase content of m-phenoxy benzaldehyde is 98.9%-99.3%, and the purity of m-phenoxy benzaldehyde is high.
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Paragraph 0077-0078
(2021/04/17)
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- Preparation method of m-phenoxy benzaldehyde
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The invention provides a preparation method of m-phenoxy benzaldehyde, and belongs to the technical field of organic synthesis. The preparation method provided by the invention comprises the following steps: condensing m-cresol serving as a raw material with halogenated benzene to obtain m-phenoxytoluene, reacting the m-phenoxytoluene with chlorine to chloridize methyl to obtain a m-phenoxytoluene chloro product, oxidizing the m-phenoxytoluene chloro product through Komblum to obtain an oxide of the m-phenoxytoluene chloro product, and directly hydrolyzing the m-phenoxytoluene chloro product without separation to obtain the product m-phenoxy benzaldehyde. The preparation method provided by the invention has the advantages that the raw materials are cheap and easily available, the yield is high, the product quality meets the market demand, the problems of high raw material price, many side reactions, many impurities, low yield, large wastewater amount and serious environmental pollution in the traditional process are solved, and the production cost of m-phenoxybenzaldehyde is greatly reduced. Data of the embodiment shows that the total yield of m-phenoxybenzaldehyde obtained by the preparation method provided by the invention is 83.5%, and the gas phase content is 99.3%.
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Paragraph 0090-0091
(2021/04/28)
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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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- Synthesis of new Zn (II) complexes for photo decomposition of organic dye pollutants, industrial wastewater and photo-oxidation of methyl arenes under visible-light
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Synthesis of new Schiff's base Zn-complexes for photo-oxidation of methyl arenes and xylenes are reported under visible light irradiation conditions. All the synthesized new ligands and Zn-complexes are thoroughly characterized with various spectral analyses and confirmed as 1:1 ratio of Zn and ligand with distorted octahedral structure. The bandgap energies of the ligands are higher than its Zn-complexes. These synthesized new Zn(II) complexes are used for the photo-fragmentation of organic dye pollutants, photodegradation of food industrial wastewater and oxidation of methyl arenes which are converted into its respective aldehydes with moderate yields under visible light irradiation. The photooxidation reaction dependency on the intensity of the visible light was also studied. With the increase in the dosage of photocatalyst, the methyl groups are oxidized to get aldehydes and mono acid products, which are also identified from LC-MS data. Finally, [Zn(PPMHT)Cl] is with better efficiency than [Zn(PTHMT)Cl] and [Zn(MIMHPT)Cl] for oxidation of methyl arenes is reported under visible-light-driven conditions.
- Ahemed, Jakeer,Bhongiri, Yadagiri,Chetti, Prabhakar,Gade, Ramesh,Kore, Ranjith,Pasha, Jakeer,Pola, Someshwar,Rao D, Venkateshwar
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- A Magnetically Recyclable Palladium-Catalyzed Formylation of Aryl Iodides with Formic Acid as CO Source: A Practical Access to Aromatic Aldehydes
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A magnetically recyclable palladium-catalyzed formylation of aryl iodides under CO gas-free conditions has been developed by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored- palladium(II) complex [2P-Fe 3O 4@SiO 2-Pd(OAc) 2] as catalyst, yielding a wide variety of aromatic aldehydes in moderate to excellent yields. Here, formic acid was employed as both the CO source and the hydrogen donor with iodine and PPh 3as the activators. This immobilized palladium catalyst can be obtained via a simple preparative procedure and can be facilely recovered simply by using an external magnetic field, and reused at least 9 times without any apparent loss of catalytic activity.
- You, Shengyong,Zhang, Rongli,Cai, Mingzhong
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p. 1962 - 1970
(2021/01/25)
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- Selective oxidation of alkenes to carbonyls under mild conditions
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Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- A highly stable metal-organic framework with cubane-like clusters for the selective oxidation of aryl alkenes to aldehydes or ketones
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Triazine derivatives, a class of electron-deficient π-conjugated molecules with high photochemical activity and excellent luminescent characteristics, have been utilized as a kind of electron-acceptor for the construction of molecular cages, luminescent and photochromic materials. In this paper, a novel and highly stable MOF with cubane-like clusters, [Co4(SO4)3(F)3(tpt)2(tatb)] (1) (tpt = 2,4,6-tris-(4-pyridyl)-1,3,5-triazine, H3tatb = 4,4′,4′′-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid), has been successfully synthesized based on a triazine derivative, and possesses unprecedented sulfate- and fluoride-bridged cubane-type tetranuclear cobalt clusters and a 3D + 3D → 3D open framework. Compound1shows a rather high BET surface area and exhibits excellent thermal stability and high chemical stability in common solvents and even in acidic or basic solutions (in a pH range from 4 to 12). Moreover, catalytic measurements show that compound1is an excellent heterogeneous catalyst for the selective oxidation of aryl alkenes to aldehydes or ketones with conversions of 97%.
- He, Chixian,Liu, Jiaming,Liu, Jian-Jun,Liu, Teng,Shen, Xianfu,Shen, Xiang
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p. 4667 - 4673
(2021/07/11)
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- Rapid, chemoselective and mild oxidation protocol for alcohols and ethers with recyclable N-chloro-N-(phenylsulfonyl)benzenesulfonamide
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Chlorine is the 20th most abundant element on the earth compared to bromine, iodine, and fluorine, a sulfonimide reagent, N-chloro-N-(phenylsulfonyl)benzenesulfonamide (NCBSI) was identified as a mild and selective oxidant. Without activation, the reagent was proved to oxidize primary and secondary alcohols as well as their symmetrical and mixed ethers to corresponding aldehydes and ketones. With recoverable PS-TEMPO catalyst, selective oxidation over chlorination of primary and secondary alcohols and their ethers with electron-donating substituents was achieved. The reagent precursor of NCBSI was recovered quantitatively and can be reused for synthesizing NCBSI.
- Badani, Purav,Chaturbhuj, Ganesh,Ganwir, Prerna,Misal, Balu,Palav, Amey
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supporting information
(2021/06/03)
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- Selective aerobic oxidation of benzylic and allylic alcohols catalyzed by Cu(OAc)2/TEMPO/Et2NH
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Selective oxidation of benzylic and allylic alcohols to their corresponding aldehyde/ketone derivative without affecting saturated alcohols is still a challenging endeavor in organic synthesis. Various metal complexes, especially the copper complexes in the presence of TEMPO are being used very often for such transformations under aerobic conditions, but they are not selective to allylic and benzylic alcohols. The use of copper salt for oxidation of alcohols in the absence of a ligand are very scarcely studied except for the one catalyzed by CuCl/TEMPO where chloride inhibition and lack of selective oxidation have been noted upon use of CuCl2. Herein we report a Cu(OAc)2 catalyzed and TEMPO mediated selective aerobic oxidation of benzylic and allylic alcohols to aldehyde/ketone in the presence of Et2NH. The method avoids pre-synthesis of the catalyst as in the case of Cu(II)/(I) complexes/TEMPO catalyzed oxidation reactions, requires low catalyst loading, employs cheaper copper salt, and gives excellent selectivity for oxidation of benzylic and allylic alcohols.
- Bez, Ghanashyam,Gogoi, Achinta,Pasupuleti, Bala Gangadhar
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p. 589 - 597
(2021/09/28)
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- Fe(III) superoxide radicals in halloysite nanotubes for visible-light-assisted benzyl alcohol oxidation and oxidative C[sbnd]C coupling of 2-naphthol
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Selective oxidation of benzyl alcohols to aldehydes and 2-naphthol to BINOL was achieved by activation of molecular oxygen (O2) and hydrogen peroxide (H2O2) over an iron-oxide catalyst embedded in halloysite nanotube. Electron spin resonance spectroscopy (ESR), Raman and in situ FTIR spectroscopic analysis provided direct evidence for the involvement of superoxide radical bound FeIII species in the oxidation reaction. Both the analysis suggested the end-on binding of superoxide radical with FeIII-centre. The stability of such radical bound FeIII-species in halloysite nanotube was analyzed through density functional theory (DFT) calculations. Results suggested that end-on (η1) binding was favourable by 13.5 kcal/ mol than the side-on (η2) binding mode. The formation of such reactive species was believed to play the crucial role in bringing the high selectivity in the catalytic oxidation of benzyl alcohol and oxidative C[sbnd]C coupling of 2-naphthol. UV–Vis spectroscopic studies on the oxidation of benzyl alcohol suggested for the initial adsorption of substrate molecule on the catalyst surface followed by its interaction with FeIII -superoxide/hydroperoxide species generated upon photoirradiation with visible light in presence of O2. The presence of a suitable band gap ~2.14 eV enabled the catalyst to catalyze the reaction under visible light irradiation. Both the reactions (benzyl alcohol and 2-naphthol oxidation) were tested in presence of both O2 and H2O2 as oxidants at ambient temperature. The influence of different parameters like rate of oxygen flow, amount of peroxide, nature of solvent, and catalyst amount on the conversion and selectivity of the reactions were studied to understand their role in the catalytic reactions. Successful oxidation of 2-naphthol with H2O2 as oxidant was a real success to overcome the limitations associated with this reaction using H2O2 as oxidant.
- Bania, Kusum K.,Baruah, Manash J.,Bora, Tonmoy J.,Dutta, Rupjyoti,Guha, Ankur Kanti,Roy, Subhasish
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- La(OH)3nanoparticles immobilized on Fe3O4@chitosan composites as novel magnetic nanocatalysts for sonochemical oxidation of benzyl alcohol to benzaldehyde
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This work introduces an eco-friendly method for immobilization of La(OH)3 nanoparticles on modified Fe3O4 nanoparticles. The structural and morphological characteristics of the nanocatalyst were determined by various analytical techniques including, FT-IR, EDS, FESEM, VSM and XRD. The catalytic efficiency of the Fe3O4@Cs/La(OH)3 composite as a heterogeneous nanocatalyst was evaluated by selective oxidation of benzylic alcohols to aldehydes. The optimum reaction conditions including time, temperature, nanocatalyst dosage, and solvent were investigated for ultrasound-assisted oxidation processes. Furthermore, the magnetic nanocatalyst was recovered up to seven times without considerable activity loss. Furthermore, the proposed nanocomposite had a remarkable effect on reducing the reaction time and enhancing the yield. This journal is
- Fadaeian, Manoochehr,Ghomi, Javad Safaei,Javidfar, Fereshteh
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p. 35988 - 35993
(2021/12/02)
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- Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
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We have developed a cerium-photocatalyzed aerobic oxidation of primary and secondary benzylic alcohols to aldehydes and ketones using inexpensive CeCl3 7H2O as photocatalyst and air oxygen as the terminal oxidant.
- K?nig, Burkhard,Kumar, Sumit,Stahl, Jessica,Yatham, Veera Reddy,Yedase, Girish Suresh
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supporting information
p. 1727 - 1732
(2021/08/05)
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- Combining photo-redox and enzyme catalysis for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives in one pot
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A novel strategy combining visible-light and enzyme catalysis in one pot for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives from alcohols is described for the first time. Fourteen 4H-pyrimido[2,1-b] benzothiazole derivatives were prepared with yields of up to 98% under mild reaction conditions by a simple operation. The photoorgano catalyst rose Bengal (rB) was employed to oxyfunctionalise alcohols to aldehydes. Compared with aldehydes, alcohols with more stable properties and lower cost, thus we used photocatalysis to oxidize alcohols into aldehydes. Next, the enzyme was used to further catalyze the reaction of Biginelli to produce the target product of 4H-pyrimidine [2,1-b] benzothiazole. Experimental results show that this method provides a more efficient and eco-friendly strategy for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives.
- Yu, Yuan,Lu, Wei-Fan,Yang, Zeng-Jie,Wang, Na,Yu, Xiao-Qi
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supporting information
(2020/12/25)
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- Photocatalytic oxidation 5-Hydroxymethylfurfural to 2, 5-diformylfuran under air condition over porous TiO2@MOF
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It is of significance for this society to develop and utilize sustainable energy and renewable resources. Photocatalytic the transformation of biomass exhibits a variety of seductive advantages, including cost-effectiveness, sustainability, mild reaction conditions and environment-benign properties. However, in order to obtain a relative high yield, most photocatalytic oxidation of HMF systems employ O2 as sole oxidant or adopt high light density condition, which is much higher than the natural sunlight density. In this work, we employ microwave-assisted post-synthetic metal exchange (PSE) method to synthesize porous TiO2@UIO-67-Zr/Ti composite as photocatalyst for the oxidation of HMF to DFF under air condition at low temperature (4 oC). SEM and FT-IR characterizations confirm the successful cation exchange of Ti4+ with Zr4+, and the Raman spectra confirm the existence of strong interactions between TiO2 and UIO-67-Zr/Ti. This catalyst exhibits enhanced photocatalytic performance, achieving 94% conversion with more than 70% selectivity for DFF. Moreover, this system also exhibits wide substrates compatibility.
- Liu, Jingjie,Long, Jilan,Zhou, Yu
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- One-pot, oxidative and selective conversion of benzylic silyl and tetrahydropyranyl ethers to gem-dichlorides using trichloroisocyanuric acid and triphenylphosphine as an efficient and neutral system
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A one-pot and oxidative method is described for the first time for the conversion of benzylic trimethylsilyl (TMS) and tetrahydropyranyl (THP) ethers to gem-dichlorides using trichloroisocyanuric acid (TCCA) and triphenylphosphine (PPh3) in neutral media. Various theses substrates containing electron withdrawing or donating groups can be efficiently converted to their corresponding gem-dichlorides in good to excellent yields. The present method shows a high degree of chemoselectivity, and due to its one-pot nature is in accordance with green chemistry.
- Khadem Moghaddam, Roqayeh,Aghapour, Ghasem
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p. 398 - 406
(2020/11/19)
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- Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas
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The reductive carbonylation of aryl iodides to aryl aldehydes possesses broad application prospects. We present an efficient and facile Rh-based catalytic system composed of the commercially available Rh salt RhCl3·3H2O, PPh3 as phosphine ligand, and Et3N as the base, for the synthesis of arylaldehydes via the reductive carbonylation of aryl iodides with CO and H2 under relatively mild conditions with a broad substrate range affording the products in good to excellent yields. Systematic investigations were carried out to study the experimental parameters. We explored the optimal ratio of Rh salt and PPh3 ligand, substrate scope, carbonyl source and hydrogen source, and the reaction mechanism. Particularly, a scaled-up experiment indicated that the catalytic method could find valuable applications in industrial productions. The low gas pressure, cheap ligand and low metal dosage could significantly improve the practicability in both chemical researches and industrial applications.
- Chen, Suqing,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong,Yu, Dongkun,Zhao, Xinhui
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p. 645 - 656
(2020/05/14)
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- Decarboxylative Oxygenation via Photoredox Catalysis
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The direct conversion of aliphatic carboxylic acids to their dehomologated carbonyl analogues has been accomplished through photocatalytic decarboxylative oxygenation. This transformation is applicable to an array of carboxylic acid motifs, producing ketones, aldehydes, and amides in excellent yields. Preliminary results demonstrate that this methodology is further amenable to aldehyde substrates via in situ oxidation to the corresponding acid and subsequent decarboxylative oxygenation. We have exploited this strategy for the sequential oxidative dehomologation of linear aliphatic chains.
- Faraggi, Tomer M.,Li, Wei,MacMillan, David W. C.
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p. 410 - 415
(2019/12/24)
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- Photo-oxidation coupled Kabachnik-Fields and Bigenelli reactions for direct conversion of benzyl alcohols to α-aminophosphonates and dihydropyrimidones
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A tandem one-pot solvent free approach for the direct conversion of benzyl alcohols to α-amino phosphonates and dihydropyrimidones is reported. The method relies on a metal free photo-oxidation of benzyl alcohols to benzaldehydes under UV irradiation using ammonium perchlorate followed by Kabachnik-Fields and Biginelli reactions. The reaction conditions are moderate and metal free with good substrate scope. The control experiments were performed to investigate the role of the ammonium perchlorate and molecular oxygen as oxidants. The quenching experiments in the presence of TEMPO and other radical quenchers suggest radical based mechanism.
- Ali, Gazunfor,Ara, Tabassum,Dangroo, Nisar A.,Naqvi, Tahira,Raheem, Shabnam,Rizvi, Masood Ahmad
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p. 195 - 202
(2020/04/01)
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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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- 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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p. 2895 - 2900
(2020/06/17)
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- A one-pot synthesis of benzimidazoles via aerobic oxidative condensation of benzyl alcohols with o-phenylenediamines catalyzed by [MIMPs]+Cl-/NaNO2/TEMPO
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The ionic liquid 1-methyl-3-(3-sulfopropyl)imidazolium chloride ([MIMPs]+Cl-) in combination with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and sodium nitrite (NaNO2) as a catalytic system demonstrates high efficiency in the one-pot two-step aerobic oxidative condensation of benzyl alcohols with 1,2-phenylenediamines to give benzimidazoles. Various benzimidazoles are obtained in good to excellent yields by this strategy.
- Geng, Zhenzhen,Zhang, Hong-Yu,Yin, Guohui,Zhang, Yuecheng,Zhao, Jiquan
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p. 557 - 565
(2020/03/30)
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- A mineralogically-inspired silver–bismuth hybrid material: Structure, stability and application for catalytic benzyl alcohol dehydrogenations under continuous flow conditions
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In the present contribution, we are reporting our findings on the structure, stability and synthetic applicability of a silver-containing hybrid material, which has recently been introduced by our research groups as a mineralogically-inspired novel heterogeneous catalyst. To determine how silver ions can be fixed into the structure of the catalyst, a set of experiments was designed with modification of the interlayer gallery under hydrothermal conditions. Subsequently, the stability of the material was examined in various solvents under demanding continuous flow conditions with the aim of achieving a clear picture of its applicability in organic syntheses. On the basis of the useful data obtained during the stability tests, a continuous flow methodology was developed for catalytic dehydrogenation of diversely substituted benzylic alcohols. As far as selectivity is concerned the catalyst performed superbly, while the conversions were varied from fair to extremely good.
- ?tv?s, Sándor B.,B?sz?rményi, éva,Fül?p, Ferenc,Kónya, Zoltán,Karádi, Krisztina,Kocsis, Marianna,Kukovecz, ákos,Mészáros, Rebeka,Pálinkó, István,Varga, Gábor
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- Method for reducing carboxylic acid compound into aldehyde
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The invention discloses a method for reducing a carboxylic acid compound into aldehyde. In a nitrogen atmosphere, in an organic solvent, a ligand/Cu catalyst, the carboxylic acid compound, an anhydride compound and hydrosilane are added by a one-pot method, a reaction is performed under the condition of the temperature of 20-120 DEG C for 2-20 h, after the reaction is completed, quenching and column chromatography separation are performed to obtain the product. The carboxylic acid compound can be successfully converted into aldehyde through one-pot reaction, especially unsaturated carboxylic acid can be reduced, and the reaction yield is generally relatively high. Compared with the prior art, the method has the outstanding advantages that the cheap copper salt is used as a catalyst, so that the experiment cost is greatly reduced. Meanwhile, the used method enlarges the application range of the reaction substrate, improves the compatibility of functional groups, and provides a new synthesis way for reducing the carboxylic acid compound into aldehyde.
- -
-
Paragraph 0048-0051
(2020/02/27)
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- Selective Functionalization of Styrenes with Oxygen Using Different Electrode Materials: Olefin Cleavage and Synthesis of Tetrahydrofuran Derivatives
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Electrode materials can have a significant impact on the course of an electrolysis reaction. Of particular interest is that different electrodes can generate different products from the same substrate. The electrode-material-selective transformations of styrene derivatives with molecular oxygen are reported. Platinum electrodes afford carbonyl products via cleavage of olefins, whereas tetrahydrofuran formation is achieved with carbon electrodes. A variety of different styrenes are available for both reactions. Electrolysis allows straightforward and mild chemical conversions that are metal- and oxidant-free. Electrochemical measurements illuminate the different effects of platinum and carbon electrodes on styrenes. The key to the differing reactions is probably that the oxidation potentials of the substrates are lower (higher HOMO energy) on carbon electrodes than on platinum electrodes. The adsorption of the substrates on carbon electrodes can also promote tetrahydrofuran formation.
- Imada, Yasushi,Okada, Yohei,Noguchi, Keiichi,Chiba, Kazuhiro
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supporting information
p. 125 - 129
(2018/12/05)
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- Organosuperbase dendron manganese complex grafted on magnetic nanoparticles; heterogeneous catalyst for green and selective oxidation of ethylbenzene, cyclohexene and oximes by molecular oxygen
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Magnetic Fe3O4 nanoparticles as a support were modified with an amino-terminated organosilicon and cyanoric choloride ligands. The novel manganese complex was grafted on modified magnetic support (Mn(II)-Met@MMNPs). The nanocatalyst structure, particle size, morphology and surface properties was well characterized by elemental analysis, ICP-AES, AAS, EDS, FT-IR, SEM, TEM, DLS, VSM, TGA, XRD and XPS. In order to develop an effective heterogeneous nanocatalyst for eco-friendly aerobic, highly active and selective catalytic reactions, synthesized nanocatalyst was applied in oxidation of various organic compounds. The catalytic performance of the manganese nanocatalyst in the aerobic oxidation of ethylbenzene (EB), cyclohexene (CYHE) and various aldoximes and ketoxime were studied. Selective aerobic oxidation of EB and CYHE and various oximes were catalyzed by the Mn-nanocatalyst using N-hydroxyphthalimide (NHPI) with molecular oxygen as the green oxidant without the need of any reducing agent, and respectively the acetophenone (AcPO) as a benzylic product, 2-cyclohexene-1-one (CYHE[dbnd]O) as an allylic product and corresponding carbonyl compounds were obtained. The oxidation process has been optimized for Mn-nanocatalyst by considering the effect of different parameters such as the ratio and amount of Mn-nanocatalyst/NHPI, reaction time and solvent for achieving maximum conversion and selectivity to products. Due to their significant low cost, informal preparation, easy magnetically separation from reaction mixture, excellent catalytic performance, simple recovery and reusability without any metal leaching, the Mn-nanocatalyst has huge application prospect in selective and green oxidation process.
- Faraji, Ali Reza,Ashouri, Fatemeh,Hekmatian, Zahra,Heydari, Somayyeh,Mosazadeh, Sima
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- A Simple, Mild and General Oxidation of Alcohols to Aldehydes or Ketones by SO2F2/K2CO3 Using DMSO as Solvent and Oxidant
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A practical, general and mild oxidation of primary and secondary alcohols to carbonyl compounds proceeds in yields of up to 99% using SO2F2 as electrophile in DMSO as both the oxidant and the solvent at ambient temperature. No moisture- and oxygen-free conditions are required. Stoichiometric amount of inexpensive K2CO3, which generates easy to separate by-products, is used as the base. Thus, 5-gram scale runs proceeded in nearly quantitative yields by a simple filtration as the work-up. The use of a polar solvent such as DMSO, which usually promotes competing Pummerer rearrangement, is also noteworthy. This protocol is compatible with a variety of common N-, O-, and S-functional groups on (hetero)arene, alkene and alkyne substrates (68 examples). The protocol was applied (99% yield) to a formal synthesis of the important cholesterol-lowering drug Rosuvastatin. (Figure presented.).
- Zha, Gao-Feng,Fang, Wan-Yin,Leng, Jing,Qin, Hua-Li
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supporting information
p. 2262 - 2267
(2019/04/17)
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- A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium
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A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study.
- Thiruvengetam, Prabaharan,Chakravarthy, Rajan Deepan,Chand, Dillip Kumar
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p. 123 - 133
(2019/07/19)
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- Aerobic alcohol oxidation catalyzed by CuO-rectorite/TEMPO in water
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An environmentally benign CuO-rectorite was prepared by calcining the co-precipitation product of Cu2+ with an acid-activated rectorite at pH 6. It could be well dispersed in water and used as a co-catalyst with TEMPO to selectively aerobically oxidize alcohols to aldehydes. The conversion of most primary benzylic alcohols was very high under optimized conditions. Interestingly, the oxidation protocol also allowed highly selective transformation of benzylic alcohols containing a phenolic hydroxyl group into the corresponding aldehydes. Additionally, very little copper was leached from the catalyst during the catalytic reaction. CuO-rectorite could be reused by centrifugation and washed with acetonitrile and water. At the same time, its catalytic activity remained high.
- Liu, Wanghui,Yang, Jianhong,Cai, Jun
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p. 549 - 561
(2018/10/15)
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- Cobalt tungsten oxide hydroxide hydrate (CTOHH) on DNA scaffold: An excellent bi-functional catalyst for oxygen evolution reaction (OER) and aromatic alcohol oxidation
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A material with interdisciplinary properties is of wide interest for use in environmental applications. Currently, hydrogen generation by electrolysis and formation of carbonyl derivatives from alcohols are two different fields that focus on energy and environmental applications. In this work, a new material, Cobalt Tungsten Oxide Hydroxide Hydrate (CTOHH) on deoxyribonucleic acid (DNA) scaffold having chain-like morphology has been prepared for the first time by a facile microwave heating method. The same CTOHH was also prepared without the DNA scaffold and resulted in irregular aggregated molecular structures. Further, both CTOHH-DNA and CTOHH were converted into CoWO4-DNA and CoWO4, respectively by annealing them at a temperature of 600 °C. All the four catalysts were used for electrocatalytic oxygen evolution reaction (OER) and for oxidation of aromatic alcohols. In OER, CTOHH-DNA delivered fruitful results compared to all other electrocatalysts. For attaining a current density of 10 mA cm-2, it just required an overpotential of 355 mV with a Tafel slope value of 47.5 mV dec-1. Similarly, all four catalysts were also analyzed for selective and controlled oxidation of aromatic alcohols to their respective aldehydes and ketones using molecular oxygen as a green oxidant where CTOHH-DNA showed better results. Chemo-selectivity has been observed for CTOHH-DNA in the co-presence of hydroxyl and cyano functional groups. The durability of CTOHH-DNA was analyzed and it showed excellent catalytic activity retention up to five cycles.
- Kumaravel, Sangeetha,Thiruvengetam, Prabaharan,Ede, Sivasankara Rao,Karthick,Anantharaj,Sam Sankar, Selvasundarasekar,Kundu, Subrata
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supporting information
p. 17117 - 17131
(2019/11/26)
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- A mild aerobic oxidation of benzyl alcohols and oxidative decarboxylation of phenylacetic acids by cellulose-supported Ag-Ag2S nanoparticles
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Synthesis, characterization and catalytic activity of Ag-Ag2S nanoparticles supported on environmentally benign cellulose matrix has been discussed. The nanoparticles carry out controlled oxidation of benzylic alcohols to aldehydes at room temperature. Same nanoparticles also carry out oxidative decarboxylation of phenylacetic acid and decarboxylation of mandelic acid derivatives to corresponding aldehydes under comparatively milder conditions. Stability and recyclability of the catalyst has been studied. The advantages of the catalyst developed in this work over other previous reports include room temperature or comparatively low temperature reaction, shorter reaction times, no requirement of stoichiometric oxidant or ligands, use of green solvents, functional group tolerance, and recyclability.
- Hussain, Farhaz Liaquat,Suri, Mrinaly,Namdeo, Ashutosh,Borah, Geetika,Dutta, Dipanka,Goswami, Tridip,Pahari, Pallab
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- Photocatalytic oxidation of aromatic alcohols over silver supported on cobalt oxide nanostructured catalyst
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In this paper, we report an in-situ synthesis of silver supported on cobalt oxide (Ag/Co3O4) nanoparticles (NPs) and studied the catalytic activity of this material as an eco-friendly, simple, recyclable and efficient catalyst for one-pot photocatalytic oxidation of aromatic alcohols. Ag nanoparticles with the sizes of 2–5 nm supported on spherical Co3O4 with the radius between 40 and 60 nm were synthesized by homogeneous chemical precipitation followed by hydrothermal heating. The as-synthesized catalyst was thoroughly characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and N2 adsorption-desorption isotherm (BET) analysis. It was observed that the catalysts with 1 wt% of silver loading shows high activity and selectivity toward the target aldehyde product. The effects of different reaction parameters such as reaction time, oxidant and solvent were investigated and studied in detail. The synergistic effect between the surface Ag NPs and Co3O4 nanospheres plays a vital role toward very high catalytic activity.
- Ji, Xianbing,Chen, Yinxia,Paul, Bappi,Vadivel
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p. 583 - 592
(2019/01/08)
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- A Transition-Metal-Free One-Pot Cascade Process for Transformation of Primary Alcohols (RCH2OH) to Nitriles (RCN) Mediated by SO2F2
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A new transition-metal-free one-pot cascade process for the direct conversion of alcohols to nitriles was developed without introducing an “additional carbon atom”. This protocol allows transformations of readily available, inexpensive, and abundant alcohols to highly valuable nitriles.
- Jiang, Ying,Sun, Bing,Fang, Wan-Yin,Qin, Hua-Li
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supporting information
p. 3190 - 3194
(2019/05/21)
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- Iron-catalyzed oxidative C-C(vinyl) σ-bond cleavage of allylarenes to aryl aldehydes at room temperature with ambient air
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A general and selective iron-catalyzed allylic C-C(vinyl) σ-bond cleavage of allylarenes without the assistance of heteroatoms to give aryl aldehydes is reported. The unstrained carbon-carbon single bond cleavage reaction uses ambient air as the sole oxidant, proceeds efficiently at room temperature, and allows for exceptional functional-group tolerance, which addresses the long-standing challenges of current C-C bond cleavage/functionalization. Notably, the method enables rapid late-stage oxidation of complex bioactive molecules and can be used to expedite syntheses of natural products (vanillin and glucovanillin) from readily available chemical feedstocks.
- Liu, Binbin,Cheng, Lu,Hu, Penghui,Xu, Fangning,Li, Dan,Gu, Wei-Jin,Han, Wei
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p. 4817 - 4820
(2019/05/02)
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- The Rearrangement of Peroxides for the Construction of Fluorophoric 1,4-Benzoxazin-3-one Derivatives
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An unprecedented skeletal rearrangement of 3-(tert-butylperoxy)indolin-2-one using a tin catalyst has been developed. This rearrangement is highly selective to afford a series of fluorophoric (Z)-2-arylidene and alkylidene-2H-benzo[b][1,4]oxazin-3(4H)-one derivatives in good to excellent yield. In contrast with Sn(OTf)2, the reaction of 3-(tert-butylperoxy)indolin-2-one derivatives with FeCl3 afforded the Hock fragmentation product via C-C bond cleavage.
- Chaudhari, Moreshwar B.,Chaudhary, Atul,Kumar, Vishnupriya,Gnanaprakasam, Boopathy
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supporting information
p. 1617 - 1621
(2019/03/20)
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- Copper-Catalyzed Oxidative Difunctionalization of Terminal Unactivated Alkenes
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The copper(II)-promoted free-radical oxidative difunctionalization of terminal alkenes to access ketoazides by utilizing molecular oxygen has been reported. A series of styrene derivatives have been evaluated and were found to be compatible to give the desired difunctionalized products in moderate to good yields. The role of molecular oxygen both as an oxidant and oxygen atom source in this catalytic transformation has been unquestionably demonstrated by 18O-labeling studies and a radical mechanistic pathway involving the oxidative formation of azidyl radicals is also designed. This environment-friendly catalytic oxidative protocol can transform aldehyde to nitrile.
- Hussain, Muhammad Ijaz,Feng, Yangyang,Hu, Liangzhen,Deng, Qingfu,Zhang, Xiaohui,Xiong, Yan
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supporting information
p. 7852 - 7859
(2018/05/30)
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- Copper diisobutyl-t-butoxyaluminum hydride: A novel reagent for chemoselective reduction of tertiary amides over esters
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We demonstrate that copper diisobutyl-t-butoxyaluminum hydride, readily prepared from lithium diisobutyl-t-butoxyaluminum hydride and CuI, effectively and chemoselectively reduces tertiary amides over esters at ambient temperature, affording the corresponding aldehydes in excellent yields.
- Im, So Hee,Shin, Won Kyu,Jaladi, Ashok Kumar,An, Duk Keun
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p. 2335 - 2340
(2018/05/16)
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- Heteropolyacid immobilized on polymer/magnetic zeolite nanocomposite as a new and recyclable catalyst for the selective oxidation of alcohols
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A new magnetic oxidation catalyst was prepared using immobilization of tungstophosphoric acid on poly(N-vinylimidazole) entrapped magnetic nanozeolite and characterized by FTIR, TGA, XRD, SEM, TEM, EDX, VSM, and ICP-OES. The resulting heterogeneous catalyst displays high catalytic performance for selective oxidation of alcohols compared to the other catalysts. The catalyst could be reused eight times without any loss of catalytic activity.
- Maleki, Maryam,Baghbanian, Seyed Meysam,Tajbakhsh, Mahmood
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p. 359 - 368
(2018/03/29)
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- Aerobic oxidations with N-hydroxyphthalimide in trifluoroacetic acid
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The potential of highly polar trifluoroacetic acid as a media for the metal-free aerobic oxidations propagated by phthalimide N-oxyl- (PINO) radical was demonstrated experimentally utilizing N-hydroxyphthalimide (NHPI) as a catalyst and HNO3 or NaNO2 as promoters. The oxidations of toluene, cyclohexane, adamantane, diamantane, and 3-oxadiamantane gave, respectively, benzaldehyde, adipic acid, 1-hydroxyadamantane, 1-hydroxydiamantane, and 9-hydroxy-3-oxadiamantane with up to 90% selectivities under high conversions of starting material. From the density functional theory computations at the M06-2X and B3LYP-D3 levels the polarized transition structures (TS) for the hydrogen abstraction from toluene and benzyl alcohol with highly electrophilic PINO-radical are substantially stabilized by non-covalent interactions (π–π stacking). Such additional stabilization is not present in the TS for the H-abstraction from benzaldehyde thus retarding its over-oxidation to benzoic acid.
- Gunchenko, Pavel A.,Li, Jing,Liu, Bifu,Chen, Hongyan,Pashenko, Alexander E.,Bakhonsky, Vladyslav V.,Zhuk, Tatyana S.,Fokin, Andrey A.
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- Reduction of aromatic nitriles into aldehydes using calcium hypophosphite and a nickel precursor
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Herein we report the reduction of aromatic nitriles into aldehydes with calcium hypophosphite in the presence of base and nickel(ii) complex in a water/ethanol mixture. This catalytic system reduced efficiently a series of aromatic nitriles bearing different functional groups such as -Cl, -CF3, -Br, -CH3, -OCH3, -COOCH2CH3, -OH and -CHO. The corresponding aldehydes were isolated in moderate to excellent yields (30-94%).
- Mouselmani, Rim,Hachem, Ali,Alaaeddine, Ali,Métay, Estelle,Lemaire, Marc
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supporting information
p. 6600 - 6605
(2018/09/25)
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- Rhodium-Catalyzed Formylation of Aryl Halides with CO2 and H2
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The reductive formylation of aryl iodides/bromides to aryl aldehydes using CO2/H2 is presented for the first time. It was realized over a catalytic system composed of RhI3 or RhI3/Pd(dppp)Cl2 (dppp = 1,3-bis(diphenyphosphino)propane) and PPh3 in the presence of Ac2O/Et3N at 100 °C, affording aromatic aldehydes in good to excellent yields, together with good functional-group tolerance and broad substrate scope. The reaction proceeds through three cascade steps, involving HCOOH formation, CO release, and formylation of aryl halides.
- Liu, Zhenghui,Yang, Zhenzhen,Yu, Bo,Yu, Xiaoxiao,Zhang, Hongye,Zhao, Yanfei,Yang, Peng,Liu, Zhimin
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supporting information
p. 5130 - 5134
(2018/09/13)
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- Designing conjugated microporous polymers for visible light-promoted photocatalytic carbon-carbon double bond cleavage in aqueous medium
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The production of valuable carbonyl compounds directly from alkenes via carbon-carbon double (CC) bond cleavage is a highly important reaction. As a promising alternative to traditional metal-catalyzed thermal reaction conditions, photocatalysis offers an environmentally friendly and sustainable synthetic strategy. However, most photocatalysts used so far were homogeneous, molecular and transition metal-based catalytic systems. Here, we report a structural design strategy of conjugated microporous polymers (CMPs) as a class of metal-free, heterogeneous, stable and reusable photocatalysts for visible light-promoted CC bond cleavage reaction. Via different electron donor and acceptor combinations in the CMP backbone structure, we systematically investigated the structural influence of the CMPs on their optical and electrochemical properties, thereby revealing the structure and performance relationship in the photocatalytic CC bond cleavage reaction. As a result, the CMP with a specific electron donor-acceptor combination containing benzothiazole as a strong electron withdrawing unit and phenyl as a weak electron donating unit was the most efficient photocatalyst. The CC bond in various alkenes, mostly styrene derivatives, could be successfully cleaved, forming aldehydes as a product with high conversion and moderate to high selectivity. The green aspect of the work is demonstrated by the utilization of visible-light, molecular oxygen as a cheap oxidant and water-based reaction medium.
- Ayed, Cyrine,Caire Da Silva, Lucas,Wang, Di,Zhang, Kai A. I.
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p. 22145 - 22151
(2018/11/24)
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- A silver NP-dispersed water extract of fly ash as a green and efficient medium for oxidant-free dehydrogenation of benzyl alcohols
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Herein, a green, efficient, and new catalytic system for dehydrogenative oxidation of benzyl alcohols using Ag nanoparticles (NPs) dispersed in water extract of fly ash (WEFA) has been developed. Various characterization techniques were performed to authenticate the formation of Ag@WEFA. The as-prepared Ag NPs (10-20 nm) were found to be dispersed in WEFA, as indicated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images. With Ag@WEFA, a variety of substituted benzyl alcohols were efficiently converted to carbonyl compounds in high yields. All the reactions were deliberately carried out without using any ligand or hazardous organic solvent. This catalytic system involving WEFA is a genuinely new concept. It is, therefore, expected to attract attention from researchers working in the areas of sustainable chemistry.
- Bhuyan, Bishal,Paul, Arijita,Devi, Meghali,Dhar, Siddhartha Sankar
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p. 1313 - 1319
(2018/01/17)
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- A Novel [Fe(acac)3] Interspersed g-C3N4 Heterostructure for Environmentally Benign Visible-Light-Driven Oxidation of Alcohols
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The present work describes facile synthesis of a novel Fe(acac)3 decorated g-C3N4 heterostructure. Mixing of iron(III) complex with g-C3N4 thorough simple ultrasonication leads to the formation of the heterostructure. The material was thoroughly characterized by FT-IR, powder XRD, SEM, TEM, UV/Vis DRS and XPS analysis. The analytical results clearly indicate that the FeIII complex is uniformly interspersed with g-C3N4. The results also suggest that there exists synergy between two components in the heterostructure for enhance catalytic performance. This novel material was used as heterogeneous catalyst for visible light driven oxidation of a number of alcohols by H2O2. The best ratio of the Fe(acac)3 and g-C3N4 is determined with PL analysis. Cold LED light was used as source of visible light. Metal complex decorated g-C3N4 heterostructured materials have been rarely used as catalysts for synthetically useful organic transformations. Thus present work on the use of this materials promises to open up new avenues in future growth in metal complex-graphitic nitride based heterostructure nanocatalysis.
- Devi, Meghali,Ganguly, Sreejeeb,Bhuyan, Bishal,Dhar, Siddhartha Sankar,Vadivel, Sethumathavan
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p. 4819 - 4825
(2018/11/27)
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