- Kinetics and mechanism of oxidation of chloramphenicol - An antibiotic drug by diperiodatocuprate(III) in aqueous alkaline medium
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The kinetics of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1:2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR and GCMS spectral studies. The reaction is of first order in DPC and CHP concentrations. As the alkali concentration increases the rate of reaction increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to slow step of the mechanism are computed and discussed. Thermodynamic quantities are also determined. by Oldenbourg Wissenschaftsverlag, Munchen.
- Hosahalli, Rajeshwari V.,Byadagi, Kirthi S.,Nandibewoor, Sharanappa T.,Chimatadar, Shivamurti A.
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- Kinetics and mechanism of ruthenium(III) catalyzed oxidation of chloromphenicol - An antibiotic drug by diperiodatocuprate(III) in aqueous alkaline medium
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The kinetics of ruthenium(III) catalyzed oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.1 mol l-1 was studied spectrophotometrically. The reaction between DPC and CHP in alkaline medium exhibits 1: 2 stoichiometry (CHP: DPC). The main oxidation products were identified by spot test, IR, NMR, and GC-MS spectral studies. The reaction is first order with respect to ruthenium(III) and DPC concentrations. The order with respect to chloramphenicol concentration varies from first order to zero order as the chloramphenicol concentration increases. As the alkali concentration increases the reaction rate increases with fractional order dependence on alkali concentration. Increase in periodate concentration decreases the rate. A mechanism adequately describing the observed regularities is proposed. The reaction constants involved in the different steps of the mechanism were calculated. The activation parameters with respect to limiting step of the mechanism are computed and discussed. Thermodynamic quantities are determined. Pleiades Publishing, Ltd., 2012.
- Hosahalli,Byadagi,Nandibewoor,Chimatadar
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- Selective photocatalytic oxidation of aromatic alcohols in solar-irradiated aqueous suspensions of Pt, Au, Pd and Ag loaded TiO2 catalysts
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The photocatalytic partial oxidation of 4-methoxybenzyl alcohol (MBA) and 4-nitrobenzyl alcohol (NBA) to corresponding aldehydes or acids was performed in water under simulated solar light at different pH's by using Pt, Au, Pd and Ag loaded Degussa P25 TiO2 catalysts, prepared by photoreduction. Bare Degussa P25 TiO2 was also used as a reference. The metal loaded TiO2 photocatalysts were characterized by XRD, TEM, ESEM and DRS techniques. The best activity and selectivity results were obtained with Pt loaded TiO2. The reactivity results show that metal loading on Degussa P25 sharply promotes the photoactivity and product selectivity towards aldehydes. Moreover, at low pH's very high aldehyde selectivities were determined for both alcohols. MBA oxidation rate was very high at low pH's, whereas an opposite trend was observed for NBA, due to the difference of the substituent group. Only from NBA a significant amount 4-nitrobenzoic acid (ca. 50%) was obtained at high pH values.
- Yurdakal, Sedat,Tek, Bilge Sina,De?irmenci, ?a?lar,Palmisano, Giovanni
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- Three N-stabilized rhodamine-based fluorescent probes for Al3+ via Al3+-promoted hydrolysis of Schiff bases
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Three probes for Al3+ detection by both fluorescence and the naked eye in acetonitrile solution were developed. The mechanism of fluorescence was based on the aluminum complexation with rhodamine and subsequent Al3+-promoted hydrolysis of the Schiff base. Theoretical calculations indicated that the aluminum complexes tend to hydrolyze to compound L6. A simple paper test strip system for the rapid monitoring of Al3+ was developed, indicating its convenient use in environmental samples.
- Ding, Peigang,Wang, Jinhui,Cheng, Junye,Zhao, Yufen,Ye, Yong
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- Fluoro-tagged osmium and iridium nanoparticles in oxidation reactions
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Osmium and iridium metal nanoparticles were supported on a fluorous organic-inorganic hybrid material prepared by the sol-gel process. Moreover, we also found that the thermolysis of the Ir4(CO)12 cluster in simply diphenylether also
- Santacruz, Lynay,Donnici, Silvia,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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- Argon plasma reduced Pt nanocatalysts supported on carbon nanotube for aqueous phase benzyl alcohol oxidation
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Carbon nanotube supported Pt nano-catalyst was prepared by facile glow discharge plasma reduction operated at room temperature. The low-temperature plasma reduced Pt nanoparticles exhibited uniform size distribution and an average particle size of around
- Zhou, Chunmei,Chen, Hong,Yan, Yibo,Jia, Xinli,Liu, Chang-Jun,Yang, Yanhui
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- Zinc chlorochromate nonahydrate [Zn(ClCrO3)2.9H2O] is a useful reagent for the solvent-free and in solution oxidative deprotection of trimethyl- and tert-butyldimethylsilyl ethers
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Primary and secondary tert-butyldimethylsilyl and trimethylsilyl ethers are oxidized to their corresponding carbonyl compounds with zinc chlorochromate nonahydrate (ZCCNH) in dichloromethane or under solvent free conditions in good yields. For comparison, we have also studied the reactions with pyridinium chlorochromate (PCC) under similar reaction conditions.
- Firouzabadi, Habib,Gholizadeh, Mostafa,Fakourpour, Mahmood
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- SECONDARY α-DEUTERIUM ISOTOPE EFFECT ON THE HYDRATION OF THE p-NITROBENZALDEHYDE
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The secondary α-deuterium isotope effect on the equilibrium constant (KD/KH) for the hydration of p-nitrobenzaldehyde is 1.39 +/- 0.05.The kinetic secondary α-deuterium isotope effect (kD/kH) for the addition of water to p-nitrobenzaldehyde is 1.18+/-0.07.This result demonstrates that there is extensive carbon-oxygen bond formation in the transition state for addition of water to the carbonyl group of p-nitrobenzaldehyde.
- Pires, Jose Ricardo,Stachissini, Antonia Sonia,Amaral, Luciano Do
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- Synthesis of novel oxime functionalized aldol products via Michael addition of oximes onto Baylis-Hillman adducts
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Triphenylphosphine-catalyzed Michael addition of oximes 2 onto Baylis-Hillman (B-H) adducts 1 led to an easy access to a novel class of oxime functionalized aldol products 3. This demonstrates the first use of an oxygen-centered nucleophile in Michael addition to B-H adducts, without touching any other functional group. Deprotection of oxime in 3 was further demonstrated using molecular hydrogen (1 atm) and 10% Pd/C (cat.) to furnish functionalized 1,3-diols 4 as potentially useful synthons with optional backbone choice (R 3 and EWG). Copyright Taylor & Francis LLC.
- Bhuniya, Debnath,Gujjary, Srinivas,Sengupta, Sujata
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- Photochemical generation of acetonitrile oxide via the C-N bond cleavage of 3-methyl-2-(4-nitrophenyl)-2H-azirine
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Acetonitrile oxide (2) is produced by the irradiation of the title azirine 1 in the presence of O2 in fluid solutions and in low-temperature matrices through the capture of the biradical 7 with O2, which is generated by the photochem
- Inui,Murata
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- Reactions of heterocyclic cations with nitrogen-containing nucleophiles. 10. Synthesis of 3,5,7-triaryl-1,2-oxazepinium perchlorates by the reaction of 2,4,6-triarylpyrylium salts with nitrones and substituted hydroxylamines
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2-Substituted 3,5,7-triaryl-1,2-oxazepinium perchlorates were obtained by the reaction of 2,4,6-triarylpyrylium salts in dimethylformamide with nitrones and N-arylhydroxylamines. The products are the first representatives of seven-membered cations with eight π electrons.
- Zvezdina,Golyanskaya,Andreeva,Popova,Medyantseva,Dorofeenko
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- Chromium(VI) based oxidants III. Ferric dichromate, polyvinylpyridine supported zinc, and ferric dichromates as new oxidizing agents
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Ferric dichromate, polyvinylpyridine supported zinc and ferric dichromates complexes are prepared and used as stable, mild, and efficient oxidizing reagents for the oxidation of different organic compounds. Ferric dichromate complex is more efficient.
- Firouzabadi,Tamami,Goudarzian,Hatam,Lakouraj
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- A DFT and experimental study of the spectroscopic and hydrolytic degradation behaviour of some benzylideneanilines
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The spectroscopic and hydrolytic degradation behaviour of some N-benzylideneanilines are investigated experimentally and theoretically via high quality density function theoretical (DFT) modelling techniques. Their absorption and vibrational spectra, accurately predicted by DFT calculations, are highly dependent on the nature of the substituents on the aromatic rings, hence, though some of their spectroscopic features are similar, energetic differences exist due to differences in their electronic structures. Whereas the o-hydroxy aniline derived adducts undergo hydrolysis via two pathways, the most energetically economical of which is initiated by a fast enthalpy driven hydration, over a conservative free energy (ΔG?) barrier of 53 kJ mol?1, prior to the rate limiting entropy controlled lysis step which occurs via a conservative barrier of ca.132 kJ mol?1, all other compounds hydrolyse via a slower two-step pathway, limited by the hydration step. Barriers heights for both pathways are controlled primarily by the structure and hence, stability of the transition states, all of which are cyclic for both pathways.
- Nelson, Peter N.,Robertson, Tahjna I.
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- Highly atom efficient synthesis of 2,2,4,5-tetrasubstituted 3(2H)-furanones having both hydroxyl and amino substituents
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We have developed a highly atom efficient synthesis of tetrasubstituted 3(2H)-furanones from easily accessible starting materials such as C,N-diarylaldonitrones and dibenzoylacetylene. Control experiments revealed that reaction of aldonitrones having electron-withdrawing groups on the C-aryl substituent in polar aprotic solvents exhibited high product selectivity while reaction temperature has only a negligible effect on product yield and selectivity.
- Antony, Jesna,Mathai, Sindhu,Natarajan, Rakesh,P. Musthafa, Sumi,Rappai, John P.,S. Devaky, Karakkattu
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supporting information
(2022/02/25)
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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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- A new catalytic approach for aerobic oxidation of primary alcohols based on a Copper(I)-thiophene carbaldimines
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We report here novel Cu(I) thiophene carbaldimine catalysts for the selective aerobic oxidation of primary alcohols to their corresponding aldehydes and various diols to lactones or lactols. In the presence of the in situ generated Cu(I) species, a persistent radical (2,2,6,6-tetramethylpiperdine-N-oxyl (TEMPO)) and N-methylimidazole (NMI) as an auxiliary ligand, the reaction proceeds under aerobic conditions and at ambient temperature. Especially the catalytic system of 1-(thiophen-2-yl)-N-(4-(trifluoromethoxy)phenyl)methanimine (ligand L2) with copper(I)-iodide showed high reactivity for all kind of alcohols (benzylic, allylic and aliphatic). In the case of benzyl alcohol even 2.5 mol% of copper loading gave quantitative yield. Beside high activity under aerobic conditions, the catalysts ability to oxidize 1,5-pentadiol to the corresponding lactol (86% in 4 h) and N-phenyldiethanolamine to the corresponding morpholine derivate lactol (86% in 24 h) is particularly noteworthy.
- Lagerspets, Emi,Valbonetti, Evelyn,Eronen, Aleksi,Repo, Timo
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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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- SBA-15 Supported 1-Methyl-2-azaadamanane N-Oxyl (1-Me-AZADO) as Recyclable Catalyst for Oxidation of Alcohol
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Herein, we designed and synthesized an SBA-15 supported 1-methyl-2-azaadamanane N-oxyl (1-Me-AZADO) and investigated its catalytic performance for selective oxidation of alcohols under Anelli's conditions. The first example of immobilization of 1-Me-AZADO was very important to advance the oxgenation effectively because this supported N-oxyl has excellent catalytic activity for oxidation of alcohols to carbonyl compounds, and more importantly, it can be conveniently recovered and reused at least 6 times without significant effect on its catalytic efficiency.
- Tian, Yangwu,Guo, Xiaqun,Li, Meichao,Li, Chunmei,Hu, Xinquan,Jin, Liqun,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu
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supporting information
p. 3928 - 3932
(2021/05/26)
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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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- A Synergistic Magnetically Retrievable Inorganic-Organic Hybrid Metal Oxide Catalyst for Scalable Selective Oxidation of Alcohols to Aldehydes and Ketones
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Herein, we report a synergistic silica coated magnetic Fe3O4 catalyst functionalized with nitrogen rich organic moieties and immobilized with cobalt metal ion (FNP-5) for selective oxidation of alcohols to aldehydes and ketones using tert-butyl hydroperoxide (TBHP) as oxidant. The catalyst was rigorously characterized via several techniques which delineate its core-shell structure, magnetic behavior, phase and crystal structure. The Co(III) acts as the active catalytic center for selective oxidation reaction. The control reactions revealed radical mechanistic pathway assisted by the synergism induced by the inorganic-organic hybrid nature of FNP-5. The other features of current protocol involve neat reaction conditions, high TOF values, scalability of product and low E-factor value (1.92). Moreover, FNP-5 could be effortlessly separated via an external magnet, displays recyclability over eight catalytic cycles and exhibits structural integrity even after rigorous use. Overall, these results manifest the understanding of synergistic architectures as sustainable surrogates for selective oxidation reactions.
- Mittal, Rupali,Awasthi, Satish Kumar
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p. 4799 - 4813
(2021/09/30)
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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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- A TEMPO-Functionalized Ordered Mesoporous Polymer as a Highly Active and Reusable Organocatalyst
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The properties of high stability, periodic porosity, and tunable nature of ordered mesoporous polymers make these materials ideal catalytic nanoreactors. However, their application in organocatalysis has been rarely explored. We report herein for the first time the incorporation of a versatile organocatalyst, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), into the pores of an FDU-type mesoporous polymer via a pore surface engineering strategy. The resulting FDU-15-TEMPO possesses a highly ordered mesoporous organic framework and enhanced stability, and shows excellent catalytic activity in the selective oxidation of alcohols and aerobic oxidative synthesis of 2-substituted benzoxazoles, benzimidazoles and benzothiazoles. Moreover, the catalyst can be easily recovered and reused for up to 7 consecutive cycles.
- Guo, Ying,Wang, Wei David,Li, Shengyu,Zhu, Yin,Wang, Xiaoyu,Liu, Xiao,Zhang, Yuan
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supporting information
p. 3689 - 3694
(2021/09/29)
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- Merging N-Hydroxyphthalimide into Metal-Organic Frameworks for Highly Efficient and Environmentally Benign Aerobic Oxidation
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Two highly efficient metal-organic framework catalysts TJU-68-NHPI and TJU-68-NDHPI have been successfully synthesized through solvothermal reactions of which the frameworks are merged with N-hydroxyphthalimide (NHPI) units, resulting in the decoration of pore surfaces with highly active nitroxyl catalytic sites. When t-butyl nitrite (TBN) is used as co-catalyst, the as-synthesized MOFs are demonstrated to be highly efficient and recyclable catalysts for a novel three-phase heterogeneous oxidation of activated C?H bond of primary and secondary alcohols, and benzyl compounds under mild conditions. Based on the high efficiency and selectivity, an environmentally benign system with good sustainability, mild conditions, simple work-up procedure has been established for practical oxidation of a wide range of substrates.
- Wang, Man,Liang, Gan,Wang, Yunhao,Fan, Tao,Yuan, Baoling,Liu, Mingxian,Yin, Ying,Li, Liangchun
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supporting information
p. 9674 - 9685
(2021/06/09)
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- Green synthesis of a vanadium(V) Schiff base complex by grinding method: study on its catalytic and anti-bacterial activity
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A facile protocol was developed for the green synthesis of a Schiff base and its vanadium(V) complex. The compounds were derived from salicylaldehyde, diethylenetriamine and vanadyl sulfate by applying grinding method to overcome environmental issues with solvents. The reactions took place rapidly and products were isolated pure. The compounds were characterized with elemental, EDX, mass spectrometry, magnetic susceptibility, molar conductance, UV-vis, FTIR and NMR analysis. The synthesized vanadium(V) complex was an efficient and selective catalyst towards oxidation of organic sulfides and alcohols. The oxidation reactions were conducted under microwave irradiation as well as conventional heating. A reaction mechanism has been proposed for the catalytic oxidation reactions. The mechanism was further established by using GAUSSIAN16 suite. The complex also showed good anti-bacterial activity against Gram-positive and Gram-negative bacteria.
- Boruah, Jeena Jyoti,Bhatt, Zankhana S.,Nathani, Chirag R.,Bambhaniya, Vaishali J.,Guha, Ankur Kanti,Das, Siva Prased
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p. 2055 - 2068
(2021/06/27)
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- Tunable Artificial Enzyme-Cofactor Complex for Selective Hydrolysis of Acetals
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Enzymes frequently use unimpressive functional groups such as weak carboxylic acids for efficient, highly selective catalysis including hydrolysis of acetals and even amides. Much stronger acids generally have to be used for such purposes in synthetic systems. We report here a method to position an acidic group near the acetal oxygen of 2-(4-nitrophenyl)-1,3-dioxolane bound by an artificial enzyme. The hydrolytic activity of the resulting artificial enzyme-cofactor complex was tuned by the number and depth of the active site as well as the hydrophobicity and acidity of the cofactor. The selectivity of the complex was controlled by the size and shape of the active site and enabled less reactive acetals to be hydrolyzed over more reactive ones.
- Bose, Ishani,Fa, Shixin,Zhao, Yan
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p. 1701 - 1711
(2021/02/05)
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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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- N-Heterocyclic Carbene Catalyzed Ester Synthesis from Organic Halides through Incorporation of Oxygen Atoms from Air
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Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O-containing compounds. Demonstrated here is a novel N-heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O-atoms from O2. Mechanistic studies prove that the deoxy Breslow intermediate generated in situ is oxidized to a Breslow intermediate for further transformation by this oxidative protocol. This method broadens the field of NHC catalysis and promotes oxygenation reactions with O2.
- Tan, Hui,Wang, Shen-An,Yan, Zixi,Liu, Jianzhong,Wei, Jialiang,Song, Song,Jiao, Ning
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supporting information
p. 2140 - 2144
(2020/12/01)
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- SBA-15 Supported Silver Catalyst for the Efficient Aerobic Oxidation of Toluene Under Solvent-Free Conditions
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The efficient SBA-15 supported silver catalysts(Ag/SBA-15) were prepared and characterized by ICP-OES, XRD, TEM, SEM, XPS and N2 adsorption–desorption techniques. The catalysts exhibited an excellent catalytic activity for the aerobic oxidation of toluene to benzaldehyde under solvent-free conditions. Conversion of toluene and selectivity of benzaldehyde were 50% and 89% respectively over catalyst with 9.1 wt% Ag loading (10Ag/SBA-15). A wide range of substrates were tolerated under the selected reaction conditions. The kinetic study shows that the oxidation of toluene over 10Ag/SBA-15 is pseudo-first-order reaction and the activation energy Ea is 45.1?kJ/mol. A plausible mechanism involving oxygen free radicals was proposed for the aerobic oxidation reaction. Compared with the traditional method, the newly designed heterogeneous catalytic system shows better economic applicability, environmental friendliness and broader application prospects. Graphical abstract: [Figure not available: see fulltext.]
- Chen, Lei,Chen, Yanjiao,Dai, Xuan,Guo, Jiaming,Peng, Xinhua
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- Photo-tunable oxidation of toluene and its derivatives catalyzed by TBATB
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In this report, tetrabutylammonium tribromide (TBATB) was introduced as an efficient visible light active catalyst to carry out the aerobic oxidation of toluene, its derivatives, and some of methyl arenes to benzaldehydes, benzoic acids and ketones in good to high yields. All the oxidation reactions were performed under mild conditions using oxygen as a green oxidant, a catalytic amount of TBATB under blue (460 nm), royal blue (430 nm), and violet LED (400 nm) irradiation. It was found that the reactions selectivity was significantly affected by changing the solvent (from CH3CN to EtOAc) and LED wavelength (from blue to violet). In the following, our mechanistic studies revealed that the visible light oxidation of toluenes and methyl arenes over TBATB could be following a benzyl peroxy radical intermediate.
- Mardani, Atefeh,Kazemi, Foad,Kaboudin, Babak
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- Core-shell Co-MOF-74@Mn-MOF-74 catalysts with Controllable shell thickness and their enhanced catalytic activity for toluene oxidation
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A series of core-shell Co-MOF-74@Mn-MOF-74 samples with different shell thicknesses were prepared by the seed growth method, which were characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), inductively coupled plasma mass spectrometry (ICP-MS), X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and scanning electron microscopy (SEM). The shell thickness of these MOF samples were successfully controlled by adjusting the mass ratio between MnCl2·4H2O and Co-MOF-74. On this basis, these MOFs were applied to the catalytic oxidation of toluene. The results showed that with the growth of Mn-MOF-74 in the outer layer of Co-MOF-74, the oxidative selectivity of the substrate to benzaldehyde was greatly improved for the synergy between the core layer and shell layer. The conversion of toluene was 22.4%, and the selectivity of benzaldehyde was 98.1%. In addition, the catalyst can transform various substituted toluene into the corresponding aldehydes in highly selectivity and still keep good stability after four catalytic cycles. The selectivity of the corresponding aldehyde is generally above 80%.
- Gu, Xiangyu,Huang, Cheng,Xu, Zengchuang,Wu, Hao,Dong, Ruilan,Liu, Rui,Chen, Jing,Zhu, Hongjun
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- PhSe(O)OH/NHPI-catalyzed oxidative deoximation reaction using air as oxidant
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A novel oxidative deoximation method was developed in this article. Compared with the reported organoselenium-catalyzed oxidative deoximation reaction, this reaction employed N-hydroxyphthalimide (NHPI) as the co-catalyst, so that the oxidative deoximation reaction could utilize air as oxidant in the green DMC solvent under mild reaction conditions. Control experiments and X-ray photoelectron spectroscopy (XPS) analysis results indicated that NHPI was essential for activating the catalytic organoselenium species. It could accelerate the activation of molecular oxygen in air to promote the reaction process. The reaction can avoid metal residues in product and is of potential application values in pharmaceutical industry due to the transition metal-free process.
- Shi, Yaocheng,Wang, Feng,Yang, Chenggen,Yu, Lei
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- Nitration of deactivated aromatic compounds via mechanochemical reaction
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A variety of deactivated arenes were nitrated to their corresponding nitro derivatives in excellent yields under high-speed ball milling condition using Fe(NO3)3·9H2O/P2O5 as nitrating reagent. A radical involved mechanism was proposed for this facial, eco-friendly, safe, and effective nitration reaction.
- Wu, Jian-Wei,Zhang, Pu,Guo, Zhi-Xin
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supporting information
(2021/05/05)
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- Hydroxyl radical-mediated oxidative cleavage of CC bonds and further esterification reaction by heterogeneous semiconductor photocatalysis
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A hydroxyl radical-mediated aerobic cleavage of alkenes and further sequence esterification reaction for the preparation of carbonyl compounds have been developed by using tubular carbon nitride (TCN) as a general heterogeneous photocatalyst under an oxygen atmosphere with visible light irradiation. This protocol has an excellent substrate scope and gives the desired aldehydes, ketones and esters in moderate to high yields. Importantly, this metal-free procedure employed photogenerated hydroxyl radicals in situ as green oxidation active species, avoiding the present additional initiators. The reaction could be carried out under solar light irradiation and was applicable to large-scale reactions. Furthermore, the recyclable TCN catalyst could be used several times without a significant loss of activities.
- Hong, Mei,Jia, Rui,Miao, Hongyan,Ni, Bangqing,Niu, Tengfei,Wang, Hui
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p. 6591 - 6597
(2021/09/10)
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- Decatungstate-mediated solar photooxidative cleavage of CC bonds using air as an oxidant in water
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With the increasing attention for green chemistry and sustainable development, there has been much interest in searching for greener methods and sources in organic synthesis. However, toxic additives or solvents are inevitably involved in most organic transformations. Herein, we first report the combination of direct utilization of solar energy, air as the oxidant and water as the solvent for the selective cleavage of CC double bonds in aryl olefins. Various α-methyl styrenes, diaryl alkenes as well as terminal styrenes are well tolerated in this green and sustainable strategy and furnished the desired carbonyl products in satisfactory yields. Like heterogeneous catalysis, this homogeneous catalytic system could also be reused and it retains good activity even after repeating three times. Mechanism investigations indicated that both O2- and 1O2 were involved in the reaction. Based on these results, two possible mechanisms, including the electron transfer pathway and the energy transfer pathway, were proposed.
- Du, Dongdong,Luo, Junfei,Shi, Sanshan,Xie, Pan,Xue, Cheng
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p. 5936 - 5943
(2021/08/23)
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- Photo-induced oxidative cleavage of C-C double bonds for the synthesis of biaryl methanoneviaCeCl3catalysis
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A Ce-catalyzed strategy is developed to produce biaryl methanonesviaphotooxidative cleavage of C-C double bonds at room temperature. This reaction is performed under air and demonstrates high activity as well as functional group tolerance. A synergistic Ce/ROH catalytic mechanism is also proposed based on the experimental observations. This protocol should be the first successful Ce-catalyzed photooxidation reaction of olefins with air as the oxidant, which would provide inspiration for the development of novel Ce-catalyzed photochemical synthesis processes.
- Xie, Pan,Xue, Cheng,Du, Dongdong,Shi, SanShan
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supporting information
p. 6781 - 6785
(2021/08/20)
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- Method for generating benzaldehyde by catalyzing alpha-monosubstituted styrene to be oxidized by N-hydroxyphthalimide
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The invention discloses a method for generating benzaldehyde by catalyzing alpha-mono-substituted styrene to be oxidized through N-hydroxyphthalimide. According to the method, N-hydroxyphthalimide isused as a catalyst, oxygen is used as an oxidizing agent, and an alpha mono-substituted styrene compound is oxidized in an organic solvent to obtain the benzaldehyde derivative. The method has the advantages of simple reaction operation, low cost, mild conditions, high yield, no heavy metal pollution and the like.
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Paragraph 0051-0053
(2021/01/24)
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- Aerobic oxidative C?C bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst
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High valency iron-containing perovskite catalyst BaFeO3-dcould efficiently promote the additive-free oxidative C?C bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O2as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.
- Shibata, Satomi,Kamata, Keigo,Hara, Michikazu
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p. 2369 - 2373
(2021/04/22)
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- g-C3N4@Ce-MOF Z-scheme heterojunction photocatalyzed cascade aerobic oxidative functionalization of styrene
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A special composite of the cerium-based metal-organic framework (Ce-UiO-66) modified with graphitic carbon nitride nanosheets (g-C3N4) has been synthesized. In order to make a comparison, a series of composites comprising g-C3N4and Ce-MOF were synthesized as well. Their structural features were investigated using Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), sorption of nitrogen (BET and BJH), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray fluorescence spectroscopy (XRF) and diffuse reflectance UV-Vis spectroscopy (UV-Vis DRS) and electron spin resonance (ESR) techniques. According to the obtained results, it was found that nanosheets of mesoporous g-C3N4act as linkers between the cerium sites, playing a critical role in the formation of composites. In fact, the embedded g-C3N4nanoparticles in the Ce-MOF cause a new kind of meso-porosity. Moreover, the coordination of nitrogen atoms in the graphitic carbon nitride structure to cerium atoms of the crystal brings about substantial changes in the optical properties, increasing the photoreactivity. On the other hand, since there is a physical contact between Ce-UiO-66 and g-C3N4in the composite, the unaltered pore volume and optical properties lead to the formation of a physical mixture rather than a composite. The g-C3N4@Ce-MOF as a photocatalyst was employed in photocatalytic aerobic oxidative Hantzsch pyridine synthesis of styrene and indicated high performance under visible light. The stability and reusability of g-C3N4@Ce-MOF were also examined and showed high efficiency up to the 5th run. Besides, the PXRD and FT-IR analyses taken from the retrieved g-C3N4@Ce-MOF nanocomposite confirmed the catalyst stability after the completion of the cascade aerobic oxidative reaction. Despite the photocatalytic performance, the synergistic effect of open metal sites in the MOF as Lewis acid and nitrogen in g-C3N4have greatly improved the efficiency of the catalyst. Moreover, the study of the reaction mechanism using ESR indicates the positive effect of composite formation on the performance of the photocatalytic aerobic oxidation reaction by the superoxide radical (O2˙—), as a selective oxidant species.
- Karimia, Meghdad,Sadeghia, Samira,Gavinehroudi, Reza Ghahremani,Mohebali, Haleh,Mahjoub, Alireza,Heydari, Akbar
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p. 6671 - 6681
(2021/04/22)
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- Method for preparing aldehyde compounds by oxidative cleavage of carbon-carbon bonds of terminal alkene compounds
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The invention discloses a method for preparing aldehyde compounds by oxidizing and breaking carbon-carbon bonds of terminal alkene compounds. The method comprises the following steps: adding an alkene-terminated compound, an additive and a nitrogen-doped mesoporous carbon-loaded monatomic catalyst into a fatty primary alcohol solvent, putting into a pressure container, sealing, introducing oxygen source gas with a certain pressure, controlling the pressure of the oxygen source gas to be 0.1-1MPa and the reaction temperature to be 80-150 DEG C, and obtaining a reaction product, namely the aldehyde compound. The nitrogen-doped mesoporous carbon-loaded monatomic catalyst adopted by the invention is high in activity, the highest separation yield of the aldehyde compound as a reaction product reaches 99%, the method is wide in application range, the reaction conditions are easy to control, the catalyst can be recycled, the post-treatment is simple, and the method is suitable for industrial production.
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Paragraph 0055-0056; 0089-0090
(2021/06/06)
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- The Highly Effective Cobalt Based Metal–Organic Frameworks Catalyst for One Pot Oxidative Esterification Under Mild Conditions
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The cobalt-based metal organic frameworks (Co-MOFs) catalyst has been prepared with using terephthalic acid and 4,4′-bipyridine as organic linkers by facile solvothermal method for one pot oxidative esterification. The prepared catalyst was pyrolysed at different temperature and then applied for oxidation of aldehyde using molecular oxygen as benign oxidant under mild conditions. The Co-MOFs pyrolysed at 800?°C (denoted as Co-MOFs-800) catalyst exhibited excellent catalytic activity, selectivity and recyclability toward the oxidative esterification of benzaldehydes. Furthermore, it can be reused up to 5 runs without significant loss of activity. Graphic Abstract: [Figure not available: see fulltext.]
- Chindawong, Chakkresit,Mekrattanachai, Pagasukon,Setthaya, Naruemon,Song, Wei Guo,Zhu, Lei
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- Photoinduced Iron-Catalyzed ipso-Nitration of Aryl Halides via Single-Electron Transfer
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A photoinduced iron-catalyzed ipso-nitration of aryl halides with KNO2 has been developed, in which aryl iodides, bromides, and some of aryl chlorides are feasible. The mechanism investigations show that the in situ formed iron complex by FeSO4, KNO2, and 1,10-phenanthroline acts as the light-harvesting photocatalyst with a longer lifetime of the excited state, and the reaction undergoes a photoinduced single-electron transfer (SET) process. This work represents an example for the photoinduced iron-catalyzed Ullmann-type couplings.
- Wu, Cunluo,Bian, Qilong,Ding, Tao,Tang, Mingming,Zhang, Wenkai,Xu, Yuanqing,Liu, Baoying,Xu, Hao,Li, Hai-Bei,Fu, Hua
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p. 9561 - 9568
(2021/08/06)
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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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- Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale
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A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log KB=LAB+LBB allows equilibrium constants, KB, to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LAB) and one for Lewis basicity (LBB). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical–organic descriptors and known thermodynamic data (ΔH (Formula presented.)). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.
- Mayer, Robert J.,Hampel, Nathalie,Ofial, Armin R.
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supporting information
p. 4070 - 4080
(2021/01/29)
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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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- The: In situ fabrication of ZIF-67 on titania-coated magnetic nanoparticles: A new platform for the immobilization of Pd(ii) with enhanced catalytic activity for organic transformations
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Considering the outstanding characteristics of metal organic frameworks (MOFs) and magnetic nanoparticles, herein we report a facile approach for the synthesis of a magnetic zeolitic-imidazolate-framework-supported palladium(ii) catalyst. In brief, zeolitic imidazolate framework-67 (ZIF-67) was successfully incorporated onto the surface of titania-coated magnetic nanoparticles using ethane-1,2-diamine as a linker, and then Pd(ii) was immobilized onto this. The resulting Pd@ZIF-67-Fe3O4-TiO2 catalyst possesses a high surface area (205 m2 g-1), a large pore volume (0.10 cm3 g-1), good magnetic responsivity (10.71 emu g-1), and high stability. A comparative analysis of Pd@ZIF-67-Fe3O4-TiO2 and Pd@Fe3O4-TiO2 catalysts for the oxidation, reduction, and oxidative deprotection of oximes was done to investigate the effects of ZIF-67 on the catalytic performance of Pd species. Substantial differences in activity and stability were observed in the presence of ZIF-67, suggesting that ZIF-67 plays an important role in enhancing the activity of Pd(ii). This superior catalytic activity and stability arises due to a synergistic effect between well-dispersed palladium species and highly porous ZIF-67, which was confirmed via XPS analysis. Moreover, the catalyst retains its structure, chemical environment, and good magnetic response even after five catalytic runs, as confirmed via FTIR, XRD, XPS, and VSM studies of reused catalyst samples.
- Kaur, Manpreet,Paul, Satya,Sharma, Chandan,Sharma, Sukanya
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p. 20309 - 20322
(2021/11/22)
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- Palladium-Catalyzed Reductive Carbonylation of (Hetero) Aryl Halides and Triflates Using Cobalt Carbonyl as CO Source
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An efficient protocol for the reductive carbonylation of (hetero) aryl halides and triflates under CO gas-free conditions using Pd/Co2(CO)8 and triethylsilane has been developed. The mild reaction conditions, enhanced chemoselectivity and, easy access to heterocyclic and vinyl carboxaldehydes highlights its importance in organic synthesis.
- Dogga, Bhushanarao,Joseph, Jayan T.,Kumar, C. S. Ananda
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supporting information
p. 309 - 313
(2020/12/23)
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- Cyclohexene Promoted Efficient Biomimetic Oxidation of Alcohols to Carbonyl Compounds Catalyzed by Manganese Porphyrin under Mild Conditions?
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Selective oxidation of alcohols to corresponding carbonyl compounds is one of the most important processes both in academic and application research. As a kind of biomimetic catalyst, metalloporphyrins-catalyzed aerobic oxidation of alcohols with aldehyde as hydrogen donator is gathering much attention. However, using olefins as another kind hydrogen donator for aerobic oxidation of alcohols has not been reported. In this study, a system comprising managenese porphyrin and cyclohexene for biomimetic aerobic oxidation of alcohols to carbonyl compounds was developed. The catalytic system exhibited excellent catalytic performance and selectivity towards the corresponding products for most primary and secondary alcohols under mild conditions. Based on the results obtained from experiments as well as in situ EPR (electron paramagnetic resonance) and UV-vis spectroscopy, the role of cyclohexene was demonstrated.
- Ji, Hong-Bing,Liu, Xiao-Hui,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai
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- Selective and solventless oxidation of organic sulfides and alcohols using new supported molybdenum (VI) complex in microwave and conventional methods
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A new dioxo-molybdenum (VI) complex supported on functionalized Merrifield resin (MR-Mo) has been synthesized and characterized by elemental, scanning electron mcroscopy, energy-dispersive X-ray analysis, TGA, Brunauer–Emmett–Teller method, powder-X-ray d
- Das, Siva Prasad,Boruah, Jeena Jyoti
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- Alcohol Oxidations by Schiff Base Manganese(III) Complexes
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Asymmetric Schiff base manganese(III) complexes involving salen ligands, N,N'-bis(salicylidene)2,3-diaminopyridine, N,N'-bis(3-methoxysalicylidene)2,3-diaminopyridine, N,N'-bis(3,5-di-tert-butylsalicylidene)2,3-diaminopyridine and N,N'-bis(3,5-di-chloro-salicylidene)2,3-diaminopyridine were prepared and their catalytic activity was investigated in the oxidation of some primary and secondary alcohols. During optimization of oxidation reactions, Mn-4, bearing electron withdrawing N,N'-Bis(3,5-di-chloro-salicylidene)2,3-diaminopyridine ligand, showed higher activity than other catalysts tested. The catalytic reactions were carried out in the presence of various oxidants such as oxygen, hydrogen peroxide or tert-butyl hydroperoxide (TBHP) and additives such as acetic acid and imidazole. The oxidant/additive combination of TBHP and imidazole was shown to be effective for the oxidation process and the degree of their impact on oxidation reaction was found highly dependent on a balanced ratio between them. Mn-4 was selected as the most effective catalyst under optimized reaction conditions and revealed efficient for the oxidation of secondary alcohols.
- Neshat, Abdollah,Kakavand, Meysam,Osanlou, Farzane,Mastrorilli, Piero,Schingaro, Emanuela,Mesto, Ernesto,Todisco, Stefano
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p. 480 - 490
(2020/02/05)
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- IBX-TfOH mediated oxidation of alcohols to aldehydes and ketones under mild reaction conditions
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An efficient, practical and facile procedure has been developed for the oxidation of primary and secondary alcohols using IBX-TfOH catalytic system in 1,4-dioxane at ambient temperature. The reaction affords quantitative yields of the corresponding carbonyl compounds without the formation of over oxidized products. The present synthetic protocol is compatible with a variety of substrates having arene, heteroarene and alkene functionalities. The developed synthetic protocol can be used for higher scale reactions as evident by the oxidation of alcohol at 1 g scale in higher yields by a simple filtration process.
- Kumar, Kamlesh,Kumar, Prashant,Joshi, Penny,Rawat, Diwan S
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supporting information
(2020/03/04)
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- Solvent-free, microwave assisted oxidation of alcohols with 4-hydroxypyridinium chlorochromate functionalized silica gel
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4-Hydroxypyridinium chlorochromate functionalized silica gel was found to be an efficient and reusable oxidant for the very fast oxidation of primary and secondary alcohols to the corresponding carbonyl compounds under solventfree conditions and microwave irradiation in excellent yields.
- AHMADI, Sayed Ali,GHALEHBANDI, Shermineh Sadat,GHAZANFARI, Dadkhoda,SHEIKHHOSSEINI, Enayatollah
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p. 283 - 289
(2020/10/06)
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- Amine-functionalized metal-organic framework-based Pd nanoparticles: Highly efficient multifunctional catalysts for base-free aerobic oxidation of different alcohols
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A palladium (Pd) nanoparticle containing a metal organic framework (MOF) is described as a highly efficient multifunctional catalyst for the aerobic oxidation of different aliphatic, aromatic and heteroaromatic alcohols in toluene. The catalytic efficienc
- Taher, Abu,Susan, Md. Abu Bin Hasan,Begum, Noorjahan,Lee, Ik-Mo
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p. 19113 - 19121
(2020/11/23)
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- A tunable synthesis of either benzaldehyde or benzoic acid through blue-violet LED irradiation using TBATB
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In this paper, a highly efficient, metal-free, and homogeneous method for the selective aerobic photooxidation of alcohols and photooxidative-desilylation of tert-butyldimethylsilyl ethers (TBDMS) in the presence of tetrabutylammonium tribromide (TBATB) under irradiation of visible light was reported. The light source: blue (460 nm) and violet (400 nm) LED, can control selective oxidation to aldehyde or carboxylic acid.
- Mardani, Atefeh,Heshami, Marouf,Shariati, Yadollah,Kazemi, Foad,Abdollahi Kakroudi, Mazaher,Kaboudin, Babak
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- A cyclometalated Ir(iii)-NHC complex as a recyclable catalyst for acceptorless dehydrogenation of alcohols to carboxylic acids
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In this work, we have synthesized two new [C, C] cyclometalated Ir(iii)-NHC complexes, [IrCp?(C∧C:NHC)Br](1a,b), [Cp? = pentamethylcyclopentadienyl; NHC = (2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazoline-2-ylidene (a); (2-flurobenzyl)-1-(4-formylphenyl)-1H-imidazoline-2-ylidene (b)] via intramolecular C-H bond activation. The molecular structure of complex 1a was determined by X-ray single crystal analysis. The catalytic potentials of the complexes were explored for acceptorless dehydrogenation of alcohols to carboxylic acids with concomitant hydrogen gas evolution. Under similar experimental conditions, complex 1a was found to be slightly more efficient than complex 1b. Using 0.1 mol% of complex 1a, good-to-excellent yields of carboxylic acids/carboxylates have been obtained for a wide range of alcohols, both aliphatic and aromatic, including those involving heterocycles, in a short reaction time with a low loading of catalyst. Remarkably, our method can produce benzoic acid from benzyl alcohol on a gram scale with a catalyst-to-substrate ratio as low as 1?:?5000 and exhibit a TON of 4550. Furthermore, the catalyst could be recycled at least three times without losing its activity. A mechanism has been proposed based on controlled experiments and in situ NMR study.
- Borah, Dhrubajit,Das, Pankaj,Saha, Biswajit,Sarma, Bipul
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p. 16866 - 16876
(2020/12/18)
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- KMnO4-catalyzed chemoselective deprotection of acetate and controllable deacetylation-oxidation in one pot
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A novel and efficient protocol for chemoselective deacetylation under ambient conditions was developed using catalytic KMnO4. The stoichiometric use of KMnO4 highlighted the dual role of a heterogeneous oxidant enabling direct access to aromatic aldehydes in one-pot sequential deacetylation-oxidation. The reaction employed an alternative solvent system and allowed the clean transformation of benzyl acetate to sensitive aldehyde in a single step while preventing over-oxidation to acids. Use of inexpensive and readily accessible KMnO4 as an environmentally benign reagent and the ease of the reaction operation were particularly attractive, and enabled the controlled oxidation and facile cleavage of acetate in a preceding step. This journal is
- Gurawa, Aakanksha,Kumar, Manoj,Rao, Dodla S.,Kashyap, Sudhir
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p. 16702 - 16707
(2020/10/27)
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- Catalytic Selective Oxidation of Primary and Secondary Alcohols Using Nonheme [Iron(III)(Pyridine-Containing Ligand)] Complexes
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The selective oxidation of different primary and secondary alcohols to carbonyl compounds by hydrogen peroxide was found to be catalyzed in conversion ranging from good to excellent by an iron(III) complex of a pyridine-containing macrocyclic ligand (Pc-L), without the need of any additive. The choice of the counteranion (Cl, Br, OTf) appeared to be of fundamental importance and the best results in terms of selectivity (up to 99 %) and conversion (up to 98 %) were obtained using the well-characterized [Fe(III)(Br)2(Pc-L)]Br complex, 4c. Magnetic moments in solid-state, also confirmed in solution ([D6]DMSO) by Evans NMR method, were calculated and point out to an iron metal center in the high spin state of 5/2. The crystal structure shows that the iron(III) center is coordinated by the four nitrogen atoms of the macrocycle and two bromide anions to form a distorted octahedral coordination environment. The catalytic oxidation of benzyl alcohol in acetonitrile was found occurring with better conversions and selectivities than in other solvents. The reaction proved to be quite general, tolerating aromatic and aliphatic alcohols, although very low yields were obtained for terminal aliphatic alcohols. Preliminary mechanistic studies are in agreement with a catalytic cycle promoted by a high-spin iron complex.
- Caselli, Alessandro,Gallo, Emma,Panza, Nicola,Rizzato, Silvia,Tseberlidis, Giorgio,di Biase, Armando
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supporting information
p. 6635 - 6644
(2020/10/30)
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- Clean and Selective Oxidation of Alcohols with Oxone and Phase-Transfer Catalysts in Water
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Abstract: A new, simple, metal-free, and eco-friendly procedure has been proposed forthe oxidation of alcohols with Oxone (potassium peroxymonosulfate) in water inthe presence of six phase-transfer catalysts (PTC). Phase-transfer catalystswere found to display high catalytic activity in water solution. Furthermore,the oxidation of alcohols was also carried out with relatively good conversionand selectivity in water without any catalyst.
- An, X. Q.,Kang, M.,Ma, H. C.,Yang, Y. X.,Yang, Z. W.,Zeng, W.
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p. 1790 - 1794
(2020/12/01)
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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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- Production method of p-nitrobenzaldehyde
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The invention discloses a production method of p-nitrobenzaldehyde. The method comprises: step 1, adding p-nitrotoluene to a reactor, and performing heating to make p-nitrotoluene become a molten material liquid; step 2, dropwise adding bromine into the p-nitrotoluene feed liquid until the reaction is complete; step 3, performing cooling to 40-60 DEG C, and adding an organic solvent into the reactor until the product is completely dissolved; step 4, adding a carbonate aqueous solution into the reactor, performing heating to a reflux state, performing hydrolyzing, and performing reacting for 15-20 hours; and step 5, performing stirring, cooling, crystallizing, filtering, washing and drying to obtain a finished product. The method has the advantages of having simplicity and high efficiency,improving the utilization rate of the raw materials, and increasing the yield of the product, and is suitable for preparing p-nitrobenzaldehyde.
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Paragraph 0027-0103
(2020/08/22)
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