- Ammonium Fluoroperoxomonophosphate Dihydrate, 2*2H2O. First Chemical Synthesis of a Fluorinated Peroxophosphate
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The salt 2*2H2O has been synthesised from the reaction of with 48 percent HF and 30 percent H2O2 at pH 10 - 11, maintained by the addition of aqueous ammonia, at an ice-bath temperature.The compound has been characterised by chemical analysis, i.r., and laser-Raman spectroscopic studies.Some properties of the compound are also reported.
- Bhattacharjee, Manish,Chaudhuri, Mihir K.
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- Enhanced catalytic (ep)oxidation of olefins by VO(II), ZrO(II) and Zn(II)-imine complexes; extensive characterization supported by DFT studies
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Three mononuclear di-valent VO2+, ZrO2+ and Zn2+-complexes (VOL, ZrOL and ZnL, respectively) were prepared from asymmetrical di-basic tetradentate di-imine ligand (6,6′-((1E,1′E)-((4-chloro-1,2-phenylene)bis(azaneylylidene))bis(methaneylylidene))bis(2-ethoxy phenol, H2L). To confirm the M-complexes compositions, various spectral tools (FT-IR, EI/M and UV-Vis. spectra), molar conductance, thermal, elemental analysis and pXRD analyses were accomplished. Distorted octahedral geometry was confirmed for ZnL and square pyramidal geometry was elucidated for VOL and ZrOL. Their catalytic efficiency was investigated in the epoxidation of 1,2-cyclohexene by H2O2. They exhibited moderate to excellent catalytic control. The effect of temperature, time, solvent, type of oxidant and amount of catalysts were studied in order to determine the optimal catalytic atmosphere. The catalysts screening for epoxidation of alternative cyclic and acyclic olefins at optimization was reported. The variation of central metal ions from high to low valents (Zr4+, V4+and Zn2+ ions) and their capability for oxidation control their catalytic potential are the most effective aspects in the epoxidation reaction. The catalytic oxidation of 2-aminothiophene within VOL, ZrOL and ZnL, as a first trial, by H2O2 was examined. Also, QSAR parameters and DFT studies were performed to predict the catalytic properties of VOL, ZrOL and ZnL, to assert on chosen application. Effective surface properties of VO(II) complex were promoted for progressing its catalytic activity, which already happened. The catalytic mechanism was supported by the sequenced stability difference between proposed intermediates based on the difference in their recorded formation energy from the DFT study.
- Adam, Mohamed Shaker S.,Abdel-Rahman, Laila H.,Ahmed, Hanan El-Sayed,Makhlouf,Alhasani, Mona,El-Metwaly, Nashwa M.
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- Two routes to 1,2-cyclohexanediol catalyzed by zeolites under solvent-free condition
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Two routes to 1,2-cyclohexanediol were studied. Specifically: (a) the hydrolysis of cyclohexene oxide and (b) the direct dihydroxylation of cyclohexene with aqueous hydrogen peroxide. Both reactions were carried out with zeolites as catalysts under solvent-free conditions, aiming to establish green routes for the synthesis of 1,2-cyclohexanediol. In the first route, H-Beta and H-ZSM-5 zeolites were used as catalysts, respectively. According to the results, H-ZSM-5 was a suitable catalyst for the hydrolysis of cyclohexene oxide. A 88.6?% yield of 1,2-cyclohexanediol could be obtained at a 96.2?% conversion of cyclohexene oxide under mild conditions, and the catalyst could be reused for three times. Compared with H-ZSM-5, H-Beta gave a much lower selectivity (63?%), although it was more active. In the second route, Ti-Beta zeolites with three different Ti loadings prepared via a simple two-step strategy were characterized and used. The results indicated that it was the framework Ti species which was responsible for the catalytic activity. The resultant Ti-Beta-3?% could give a 90.2?% cyclohexene conversion at a 66.2?% selectivity of 1,2-cyclohexanediol.
- Lei, Wenkang,Wu, Zaikun,Ma, Jie,Yu, Ping,Luo, Yunbai
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- Kinetic role of tert-amines in the osmium tetroxide catalyzed trimethylamine N-oxide dihydroxylation of cyclohexene
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Effect of some tert-amines on the catalytic osmium tetroxide dihydroxylation of cyclohexene in aqueous tert-butyl alcohol has been investigated. All amines have been found to retard the catalysis greatly and beyond a definite concentration of amine, the rate reaches a minimal and remains constant. The oxidation of cyclohexene is inhibited by pyridine, 2,2′-bipyridyl, and DABCO with an inverse first-order dependence whereas inhibition by triphenylamine, N,N-diethylaniline, picoline, pyrazine, hexamethylenetetraamine, and TMEDA shows an inverse partial order dependence. The involvement of dioxomonoglycolatoosmium(VI) esters and their monoamine adducts in the rate determining oxidation step was established by the linear plots of 1/Δk2 vs. 1/[L] where Δk2 is the decrease in the second-order rate constant in the presence of [L] concentration of tert-amine. The ligand-accelerated or ligand-decelerated catalysis of tert-amines in the catalytic osmium tetraoxide dihydroxylation of alkenes may vary depending on the secondary oxidant, on the alkene, and on the structure and concentration of the tert-amine.
- Erdik, Ender,Kahya, Didem
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- PROCESS FOR THE PREPARATION OF HYDROPEROXY ALCOHOLS USING A HETEROGENOUS CATALYST
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The present invention relates to a process for preparing hydroperoxy alcohols using hydrogen peroxide as an oxidant in a solvent selected from water-soluble carboxylic acids, in the presence of a metallic mixed oxide heterogeneous catalyst. It also pertains to the use of this catalyst in the synthesis of hydroperoxy alcohols.
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Page/Page column 23
(2021/07/02)
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- Oxidative cleavage of cycloalkenes using hydrogen peroxide and a tungsten-based catalyst: Towards a complete mechanistic investigation
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The identification of the intermediates and by-products produced during the oxidative cleavage of cycloalkenes in the presence of H2O2 and a tungsten-based catalyst for the production of dicarboxylic acids has been carried out under various experimental conditions. On the basis of this mechanistic investigation and previous studies from the literature, a complete reaction scheme for the formation of the reaction products and by-products is proposed. In this hypothetical mechanism, the production of a hydroperoxyalcohol intermediate accounts for the two pathways proposed by Noyori and Venturello for the formation of the targeted dicarboxylic acid. In addition, Baeyer-Villiger oxidation of the mono-aldehyde intermediate allows explaining the formation of short chain diacids observed as by-products during the reaction. Hence, the proposed mechanism constitutes a real tool for scientists looking for a better understanding and those heading to set up environmentally friendly conditions for the oxidative cleavage of cycloalkenes.
- Cousin, Tony,Chatel, Gregory,Andrioletti, Bruno,Draye, Micheline
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p. 235 - 242
(2021/01/11)
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- Tandem Lewis acid catalysis for the conversion of alkenes to 1,2-diols in the confined space of bifunctional TiSn-Beta zeolite
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The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single-pass tandem catalytic reaction. In this study, bifunctional TiSn-Beta zeolite was prepared by a simple and scalable post-synthesis approach, and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2-diols. The isolated Ti and Sn Lewis acid sites within the TiSn-Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one-step conversion of alkenes to 1,2-diols with a high selectivity of >90%. Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product. Further, the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production.
- Lei, Qifeng,Wang, Chang,Dai, Weili,Wu, Guangjun,Guan, Naijia,Hunger, Michael,Li, Landong
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p. 1176 - 1184
(2021/02/16)
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- Selective Oxidation of Cyclohexene with H2O2 Catalyzed by Resin Supported Peroxo Phosphotungstic Acid Under Mild Conditions
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Abstract: A series of modified chloromethyl polystyrene resins loaded with peroxo phosphotungstic acid catalysts were synthesized for the selective oxidation of cyclohexene. The surface of resin was enriched with high concentration quaternary ammonium salt, and grafted with a large amount of peroxo PW-anion through ion exchange. The novel resin catalyst showed excellent cyclohexene conversion and epoxide selectivity using 30% H2O2 as oxidant at ambient temperature. Furthermore, the resin catalyst exhibited excellent recycling stability, which can be reused by a simple filtration and the peroxo phosphotungstic acid did not leach into the solvent after reaction. Graphic Abstract: [Figure not available: see fulltext.]
- Liu, Jia,Yang, Guoqiang,Liu, Ying,Zhou, Zheng,Zhang, Zhibing,Hu, Xingbang
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p. 147 - 152
(2020/06/20)
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- Catalytic Performance of Zr-Based Metal–Organic Frameworks Zr-abtc and MIP-200 in Selective Oxidations with H2O2
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The catalytic performance of Zr-abtc and MIP-200 metal–organic frameworks consisting of 8-connected Zr6 clusters and tetratopic linkers was investigated in H2O2-based selective oxidations and compared with that of 12-coordinated UiO-66 and UiO-67. Zr-abtc demonstrated advantages in both substrate conversion and product selectivity for epoxidation of electron-deficient C=C bonds in α,β-unsaturated ketones. The significant predominance of 1,2-epoxide in carvone epoxidation, coupled with high sulfone selectivity in thioether oxidation, points to a nucleophilic oxidation mechanism over Zr-abtc. The superior catalytic performance in the epoxidation of unsaturated ketones correlates with a larger amount of weak basic sites in Zr-abtc. Electrophilic activation of H2O2 can also be realized, as evidenced by the high activity of Zr-abtc in epoxidation of the electron-rich C=C bond in caryophyllene. XRD and FTIR studies confirmed the retention of the Zr-abtc structure after the catalysis. The low activity of MIP-200 in H2O2-based oxidations is most likely related to its specific hydrophilicity, which disfavors adsorption of organic substrates and H2O2.
- Maksimchuk, Nataliya V.,Ivanchikova, Irina D.,Cho, Kyung Ho,Zalomaeva, Olga V.,Evtushok, Vasiliy Yu.,Larionov, Kirill P.,Glazneva, Tatiana S.,Chang, Jong-San,Kholdeeva, Oxana A.
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supporting information
p. 6985 - 6992
(2021/03/17)
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- Direct hydrothermal synthesis of Mo-containing MFI zeolites using Mo-EDTA complex and their catalytic application in cyclohexene epoxidation
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A series of Mo-containing MFI zeolites with different Mo loadings (Mo-MFI-n, n represent the initial Si/Mo molar ratio) was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA complex as the Mo source. Various characterization results demonstrated that the use of the Mo-EDTA complex is beneficial for the incorporation of more Mo species into the MFI-type zeolites. The special complexing capability of EDTA2– plays a critical role in adjusting the release rate of the Mo species to combine with the Si tetrahedron species during the zeolite growth process, thus leading to a uniform distribution of Mo in the MFI framework. In addition, a small portion of extra-framework Mo clusters may be distributed inside the channels or near the pore window of the zeolites. The catalytic properties of these Mo-containing MFI zeolites were evaluated for the epoxidation of cyclohexene with H2O2 as the oxidant. The composition-optimized catalyst, Mo-MFI-50, efficiently converted cyclohexene to the corresponding epoxide with a relatively high conversion (93%) and epoxide selectivity (82%) at 75 °C after 9 h of reaction. Moreover, the resultant Mo-containing MFI catalyst exhibited excellent structural stability and recoverability and was easily recycled by simple filtration without the need for calcination treatment.
- Chang, Xinyu,Jia, Mingjun,Miao, Songsong,Sun, Yuting,Xu, Lifen,Zhang, Haoyang
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p. 2265 - 2274
(2021/09/20)
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- Instant Cyclohexene Epoxidation Over Ni-TUD-1 Under Ambient Conditions
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Abstract: To avoid the aggregation problem and activity loss of nickel oxide (NiO) nanoparticles (NPs) in organic reactions, NiO NPs were incorporated into TUD-1 mesoporous material. One-step sol–gel preparation was applied to prepare four samples of Ni incorporated in TUD-1 silica matrix with different Ni content. The four samples with Si/Ni ratio = 100, 50, 20, and 10 were characterized by means of elemental analysis, powder X-ray diffraction (XRD), Raman spectroscopy, N2 sorption measurements, scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), and high-resolution transmission electron microscopy (HR-TEM). The characterization analysis showed that Ni2+ ions were incorporated into the silica matrix as individual isolated active sites at Ni content smaller than 2 wt%, and as nanoparticles of NiO when the loading is equal to or higher than 5 wt%. The size of NiO NPs inside the silica matrix is highly dependent on the Ni content, i.e. the size of NiO NPs when the loading was 5 wt% and 10 wt% was 5–10 and 40–60?nm, respectively. The catalytic activity of Ni-TUD-1 was investigated in the epoxidation reaction of cyclohexene at room temperature by using meta-chloroperoxybenzoic acid (m-CPBA) as an oxidant. The obtained results showed that Ni-TUD-1 exhibited superior activity in which 100% conversion of cyclohexene with > 90% selectivity towards cyclohexene oxide was obtained instantly. This result was found to benchmark not only the unsupported NiO nanoparticles, but also the reported catalysts at similar conditions. Graphic Abstract: [Figure not available: see fulltext.].
- Hamdy, Mohamed S.,Al-Zaqri, Nabil,Sahlabji, Taher,Eissa, Murad,Haija, Mohammad Abu,Alhanash, Abdullah M.,Alsalme, Ali,Alharthi, Fahad A.,Abboud, Mohamed
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p. 1612 - 1622
(2020/10/14)
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- Selective cyclohexene oxidation to allylic compounds over a Cu-triazole frameworkviahomolytic activation of hydrogen peroxide
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Utilization of metal-organic frameworks as heterogeneous catalysts is crucial owing to their abundant catalytic sites and well-defined porous structures. Highly robust [Cu3(trz)3(μ3-OH)(OH)2(H2O)4]·2H2O (trz = 1,2,4-triazole) was employed as a catalyst for liquid-phase cyclohexene oxidation with hydrogen peroxide (H2O2). Possessing the porous structure together with Lewis acid attributes from the triangular [Cu3(trz)3(μ3-OH)] center, selective oxidation of cyclohexene to allylic products gives a molar yield of 31% with 87% selectivity. According to the highly selective allylic production, the reaction over the present Cu-MOF plausibly occursviahomolytic activation of H2O2. This finding elucidates the unique features of the MOF for efficient catalysis of cyclohexene oxidation.
- Adpakpang, Kanyaporn,Bureekaew, Sareeya,Ponchai, Panyapat
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supporting information
p. 7917 - 7921
(2021/06/18)
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- Novel WO3/SO42--ZrO2–TiO2 double bridge coordination catalyst hfor oxidation of cyclohexene
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A solid super acid WO3/SO42--ZrO2–TiO2 catalyst was prepared with adjustable acidity via double bridge connection strategy for oxidation of cyclohexene (CHE) to adipic acid (AA). XRD, SEM and N2 adsorption-desorption isotherm indicated that WO3 was successfully decorated and was highly dispersed on SO42--ZrO2–TiO2 surface. An obvious stretching vibration peak (1125-1055 ?cm?1) in FT-IR illustrated that connection effect between SO42? and ZrO2–TiO2 was double bridge connection. NH3-TPD profile appeared a strong acid center peak (516 ?°C), while this center of solid super acid catalyst could reduce decomposition rate of H2O2 directly, and increase reaction time between CHE and H2O2 meanwhile. The marked catalytic performance was attributed to the synergistic effect between WO3 and SO42--ZrO2–TiO2. DFT calculation was employed to further analyze reaction process and system energy.
- Liu, Xiangxue,Wang, Ke,Liu, Baoquan,Guo, Zhenmei,Zhang, Chao,Lv, Zhiguo
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- Sterically controlling 2-carboxylated imidazolium salts for one-step efficient hydration of epoxides into 1,2-diols
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In order to overcome the disadvantages of excessive water and many byproducts in the conventional process of epoxide hydration into 1,2-diols, 2-carboxylated imidazolium salts were first adopted as efficient catalysts for one-step hydration of epoxides into 1,2-diols. By regulating the cation chain lengths, different steric structures of 2-carboxylated imidazolium salts with chain lengths from C1 to C4 were prepared. The salt with the shortest substituent chain (DMIC) exhibited better thermal stability and catalytic performance for hydration, achieving nearly 100% ethylene oxide (EO) conversion and 100% ethylene glycol (EG) selectivity at 120 °C, 0.5 h with just 5 times molar ratio of H2O to EO. Such a tendency is further confirmed and explained by both XPS analysis and DFT calculations. Compared with other salts with longer chains, DMIC has stronger interaction of CO2?anions and imidazolium cations, exhibiting a lower tendency to release CO2?and form HO-CO2?, which can nucleophilically attack and synergistically activate ring-opening of epoxides with imidazolium cations. The strong huge sterically dynamic structure ring-opening transition state slows down the side reaction, and both cations and anions stabilized the transition state imidazolium-EG-HO-CO2?, both of which could avoid excessive hydration into byproducts, explaining the high 1,2-diol yield. Based on this, the cation-anion synergistic mechanism is then proposed.
- Cheng, Weiguo,Dong, Li,Fu, Mengqian,Su, Qian,Tan, Xin,Yao, Xiaoqian,Ying, Ting,Zhang, Suojiang
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p. 2992 - 3000
(2021/05/07)
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- Catalytic role of metals supported on SBA-16 in hydrodeoxygenation of chemical compounds derived from biomass processing
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Hydrodeoxygenation (HDO) carried out at high temperatures and high hydrogen pressures is one of the alternative methods of upgrading pyrolytic oils from biomass, leading to high quality biofuels. To save energy, it is important to carry out catalytic proc
- Szczyglewska, Paulina,Feliczak-Guzik, Agnieszka,Jaroniec, Mietek,Nowak, Izabela
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p. 9505 - 9517
(2021/03/16)
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- Synthesis of Cu Single Atoms Supported on Mesoporous Graphitic Carbon Nitride and Their Application in Liquid-Phase Aerobic Oxidation of Cyclohexene
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Different loadings of Cu single atoms were anchored on a graphitic carbon nitride (g-C3N4) matrix using a two-step thermal synthesis method and applied in liquid-phase cyclohexene oxidation under mild conditions using molecular O2 as the oxidizing agent. The oxidation state of Cu was determined to be Cu+, which is in linear coordination with two neighboring nitrogen atoms at a distance of 1.9 ?. The catalyst with 0.9 wt % Cu pyrolyzed at 380 °C was found to exhibit the best catalytic performance with the highest conversion up to 82% with an allylic selectivity of 55%. It also showed high reusability over four catalytic runs without any detectable Cu leaching. Cyclohexene oxidation followed first-order kinetics with an apparent activation energy of 66.2 kJ mol-1. The addition of hydroquinone as a radical scavenger confirmed that cyclohexene oxidation proceeds via a radical mechanism. Time-resolved in situ attenuated total reflection infrared (ATR-IR) spectroscopy was carried out to qualitatively monitor the cyclohexene oxidation pathways. The comparison with the homogeneous analogue Cu(I) iodide indirectly verified the linearly N-coordinated single Cu(I) species to be the active sites for cyclohexene oxidation.
- Büker, Julia,Bitzer, Johannes,Huang, Xiubing,Kleist, Wolfgang,Muhler, Martin,Peng, Baoxiang
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p. 7863 - 7875
(2021/07/13)
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- Structural elucidation, DFT calculations and catalytic activity of dioxomolybdenum(VI) complexes with N–N donor ligand: Role of halogen atom coordinated to the molybdenum centre
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Two new isostructural mononuclear dioxomolybdenum(VI) complexes of the formula MoO2X2L [where, X = Cl (1), Br (2)] have been synthesized with a N–N donor 2-(3-methyl-5-phenyl pyrazol-1-yl) benzthiazole ligand (L). The reaction is carried out in open air and the MoVO3+ centre in the precursor molecule, MoOX3L undergoes spontaneous aerial oxidation, leading to the formation of molybdenum(VI) complexes 1 and 2. The complexes are characterized by a wide range of spectroscopic techniques (IR, UV–Vis and 1H NMR) and elemental analyses. Crystal structures of the ligand and complexes 1 and 2 have been determined by single crystal X-ray diffraction which reveal a distorted octahedral geometry around the molybdenum(VI) centre in both the complexes. The ligand and the complexes build up fascinating supramolecular assembly via several non-covalent interactions including hydrogen bonding, C–H···π and π···π interactions. Further, a detailed study of Hirshfeld surface analysis and fingerprint plots of complexes 1 and 2 are presented for understanding the intermolecular interactions involved in building self-assembled frameworks. Supportive DFT and TD-DFT calculations have also been carried out. Electrochemical properties of the complexes have been examined by cyclic voltammetry. Catalytic performance of the synthesized complexes has been evaluated for the oxidation of different olefins in the presence of hydrogen peroxide.
- Roy, Malini,Biswal, Debanjana,Pramanik, Nikhil Ranjan,Drew, Michael G.B.,Paul, Suvendu,Kachhap, Payal,Haldar, Chanchal,Chakrabarti, Syamal
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- Activation of H2O2over Zr(IV). Insights from Model Studies on Zr-Monosubstituted Lindqvist Tungstates
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Zr-monosubstituted Lindqvist-type polyoxometalates (Zr-POMs), (Bu4N)2[W5O18Zr(H2O)3] (1) and (Bu4N)6[{W5O18Zr(μ-OH)}2] (2), have been employed as molecular models to unravel the mechanism of hydrogen peroxide activation over Zr(IV) sites. Compounds 1 and 2 are hydrolytically stable and catalyze the epoxidation of C?C bonds in unfunctionalized alkenes and α,β-unsaturated ketones, as well as sulfoxidation of thioethers. Monomer 1 is more active than dimer 2. Acid additives greatly accelerate the oxygenation reactions and increase oxidant utilization efficiency up to >99%. Product distributions are indicative of a heterolytic oxygen transfer mechanism that involves electrophilic oxidizing species formed upon the interaction of Zr-POM and H2O2. The interaction of 1 and 2 with H2O2 and the resulting peroxo derivatives have been investigated by UV-vis, FTIR, Raman spectroscopy, HR-ESI-MS, and combined HPLC-ICP-atomic emission spectroscopy techniques. The interaction between an 17O-enriched dimer, (Bu4N)6[{W5O18Zr(μ-OCH3)}2] (2′), and H2O2 was also analyzed by 17O NMR spectroscopy. Combining these experimental studies with DFT calculations suggested the existence of dimeric peroxo species [(μ-?2:?2-O2){ZrW5O18}2]6- as well as monomeric Zr-hydroperoxo [W5O18Zr(?2-OOH)]3- and Zr-peroxo [HW5O18Zr(?2-O2)]3- species. Reactivity studies revealed that the dimeric peroxo is inert toward alkenes but is able to transfer oxygen atoms to thioethers, while the monomeric peroxo intermediate is capable of epoxidizing C?C bonds. DFT analysis of the reaction mechanism identifies the monomeric Zr-hydroperoxo intermediate as the real epoxidizing species and the corresponding α-oxygen transfer to the substrate as the rate-determining step. The calculations also showed that protonation of Zr-POM significantly reduces the free-energy barrier of the key oxygen-transfer step because of the greater electrophilicity of the catalyst and that dimeric species hampers the approach of alkene substrates due to steric repulsions reducing its reactivity. The improved performance of the Zr(IV) catalyst relative to Ti(IV) and Nb(V) catalysts is respectively due to a flexible coordination environment and a low tendency to form energy deep-well and low-reactive Zr-peroxo intermediates.
- Abramov, Pavel A.,Carbó, Jorge J.,Chesalov, Yuriy A.,Eltsov, Ilia V.,Errington, R. John,Evtushok, Vasilii Yu.,Glazneva, Tatyana S.,Ivanchikova, Irina D.,Kholdeeva, Oxana A.,Maksimchuk, Nataliya V.,Maksimov, Gennadii M.,Poblet, Josep M.,Solé-Daura, Albert,Yanshole, Vadim V.,Zalomaeva, Olga V.
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p. 10589 - 10603
(2021/09/02)
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- The Effect of Sulfonate Groups in the Structure of Porous Aromatic Frameworks on the Activity of Platinum Catalysts Towards Hydrodeoxygenation of Biofuel Components
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Abstract: Platinum catalysts based on porous aromatic frameworks (PAF-30 and PAF-30–SO3H) have been synthesized. Properties of the obtained catalysts have been assessed via hydrogenation of guaiacol, veratrole, and pyrocatechol at 250°С and hydrogen pressure 3.0 MPa in isopropanol medium. It has been shown that the presence of acidic sites in the catalyst significantly increases the yield of deoxygenation products. The effect of the substrate structure on the rate of its hydrodeoxygenation and the mechanism of the occurring processes have been studied. [Figure not available: see fulltext.]
- Kalinina,Kulikov,Cherednichenko,Maximov,Karakhanov
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p. 1061 - 1070
(2021/09/06)
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- Liquid-Phase Cyclohexene Oxidation with O2 over Spray-Flame-Synthesized La1?xSrxCoO3 Perovskite Nanoparticles
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La1?xSrxCoO3 (x=0, 0.1, 0.2, 0.3, 0.4) nanoparticles were prepared by spray-flame synthesis and applied in the liquid-phase oxidation of cyclohexene with molecular O2 as oxidant under mild conditions. The catalysts were systematically characterized by state-of-the-art techniques. With increasing Sr content, the concentration of surface oxygen vacancy defects increases, which is beneficial for cyclohexene oxidation, but the surface concentration of less active Co2+ was also increased. However, Co2+ cations have a superior activity towards peroxide decomposition, which also plays an important role in cyclohexene oxidation. A Sr doping of 20 at. % was found to be the optimum in terms of activity and product selectivity. The catalyst also showed excellent reusability over three catalytic runs; this can be attributed to its highly stable particle size and morphology. Kinetic investigations revealed first-order reaction kinetics for temperatures between 60 and 100 °C and an apparent activation energy of 68 kJ mol?1 for cyclohexene oxidation. Moreover, the reaction was not affected by the applied O2 pressure in the range from 10 to 20 bar. In situ attenuated total reflection infrared spectroscopy was used to monitor the conversion of cyclohexene and the formation of reaction products including the key intermediate cyclohex-2-ene-1-hydroperoxide; spin trap electron paramagnetic resonance spectroscopy provided strong evidence for a radical reaction pathway by identifying the cyclohexenyl alkoxyl radical.
- Büker, Julia,Alkan, Baris,Chabbra, Sonia,Kochetov, Nikolai,Falk, Tobias,Schnegg, Alexander,Schulz, Christof,Wiggers, Hartmut,Muhler, Martin,Peng, Baoxiang
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supporting information
p. 16912 - 16923
(2021/10/19)
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- Lipase catalysed oxidations in a sugar-derived natural deep eutectic solvent
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Chemoenzymatic oxidations involving the CAL-B/H2O2 system was developed in a sugar derived Natural Deep Eutectic Solvent (NaDES) composed by a mixture of glucose, fructose and sucrose. Good to excellent conversions of substrates like cyclooctene, limonene, oleic acid and stilbene to their corresponding epoxides, cyclohexanone to its corresponding lactone and 2-phenylacetophenone to its corresponding ester, demonstrate the viability of the sugar NaDES as a reaction medium for epoxidation and Baeyer-Villiger oxidation.
- Vagnoni, Martina,Samorì, Chiara,Pirini, Daniele,Vasquez De Paz, Maria Katrina,Gidey, Dawit Gebremichael,Galletti, Paola
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- Understanding the mechanism of N coordination on framework Ti of Ti-BEA zeolite and its promoting effect on alkene epoxidation reaction
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The function of ammonium salts on the epoxidation performance over Ti-BEA zeolite was investigated in detail. Experiments of alkene epoxidation, side reactions of epoxide and decomposition of H2O2 with or without ammonium salts were designed, and the UV-Vis spectroscopy was employed to analyze the structure of Ti-hydroperoxo species. It is revealed that the ammonia (or amines) dissociated from the ammonium salt would chelate with the linear Ti-η1(OOH) species and form a bridged Ti-η2(OOH)-R species, which is more stable, more weaker in epoxide adsorption and acidity as well. Therefore, side reactions and H2O2 decomposition would be suppressed, and both alkene conversion and epoxide selectivity would be promoted simultaneously. On the other hand, the excessive NH3?H2O (NH3/Ti>1) or NaOH bond with the Ti-η2(OOH)-R species and generate salt-like Ti-η2(OO)-M+ species, resulting in the deactivation of Ti active center. While for ammonium salts, e.g. NH4Cl, the limited dissociation degree along with the acidic environment help the Ti active center to maintain in highly active. In short, this work provides a practical Ti active center tuning method for Ti-BEA zeolite, as well as a thorough understanding of its Ti-hydroperoxo species.
- Liang, Xiaohang,Liu, Dan,Luo, Yibin,Peng, Xinxin,Shu, Xingtian,Xia, Changjiu
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- Sulfonic-functionalized MIL-101 as bifunctional catalyst for cyclohexene oxidation
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Metal-organic frameworks (MOFs) are newly emerging and versatile platforms for designing catalysts, and catalytic oxidation of cyclohexene has attracted much academic and industrial attention for the versatile reactivity of the substrate and the great importance of the various oxygenated products. Here we report the bifunctional catalytic properties of a sulfonic-containing MOF, MIL-101-SO3H, for cyclohexene oxidation. The sulfonic group and the Cr(III) site acts in a complementary or collaborative way. The Cr(III) framework promotes the oxidation to 3-hydroperoxycyclohex-1-ene (perox) and 2-cyclohexen-1-one (1-one) (route A), whereas the sulfonic group in collaboration with the Cr(III) framework promotes the oxidation to diol (route B) and also enhances further conversions in route A: from perox to 1-one, to 2-cyclohexen-1,4-dione (dione) and even to benzoquinone. With the bifunctional MOF, molecular oxygen alone cannot oxidize cyclohexene but participates as oxidant cooperating with tert-butyl hydroperoxide (TBHP) to accelerate the reactions and to alter the product distribution in favor of dione.
- Sun, Weng-Jie,Gao, En-Qing
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- Enantiotopic Discrimination by Coordination-Desymmetrized meso-Ligands
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The first examples of enantiopure catalysts that are chiral merely due to coordination of different metal ions at enantiotopic positions of an achiral meso-ligand are reported. These catalysts exhibit a pseudo-Cs symmetry and are able to catalyze reactions demanding simultaneous involvement of two catalytic sites. The latter was demonstrated by application in the asymmetric ring-opening of meso-epoxides.
- Li, Yutang,Lidskog, Anna,Armengol-Relats, Helena,Pham, Thanh Huong,Favraud, Antoine,Nicolas, Maxime,Dawaigher, Sami,Xiao, Zeyun,Ma, Dayou,Lindb?ck, Emil,Strand, Daniel,W?rnmark, Kenneth
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p. 1575 - 1579
(2020/02/04)
-
- Homo-dinuclear VO2+ and Ni2+ dihydrazone complexes: Synthesis, characterization, catalytic activity and CO2-corrosion inhibition under sustainable conditions
-
VO2+ and Ni2+ complexes (VOPHL and NiPHL) were prepared by complexation of terephthaloyl salicylidene dihydrazone (H2PHL) with VO2+ or Ni2+ ions. The chemical structures were estimated by various spectroscopic methods. Their sustainable corrosion inhibition on mild steel in NaCl solutions saturated with CO2 was investigated using potentiodynamic polarization (PDP), open circuit potential and electrochemical impedance spectroscopy (EIS) methods. H2PHL, NiPHL and VOPHL showed maximum capacity within 89.57, 97.25 and 98.22%, respectively. The PDP study refers to that they could act as mixed-type inhibitors i.e. retarded both cathodic and anodic reactions. Metal complexes displayed better inhibition than their coordinated ligand. H2PHL and its M-complexes adsorbed on C-steel surface via chemical adsorption with obeying the Langmuir model. The post-exposure investigation, for the inhibited and uninhibited C-steel surface, was elucidated using SEM /EDS. The homogeneous catalytic behavior of NiPHL and VOPHL was studied in the (ep)oxidation of unsaturated cycloalkene (1,2-cyclohexene) and Suzuki-Miyaura cross-coupling. VOPHL shows better catalytic potential in (ep)oxidation processes. NiPHL has higher catalytic efficiency towards cross-couplings. The aqueous hydrolysis of epoxy selective product could be reduced in low temperature of the (ep)oxidation processes. DFT studies were performed on H2PHL, NiPHL and VOPHL. Electronic representatives ELUMO, EHOMO energy gap (ΔE), hardness, softness and electronegativity were computed. Theoretical values are in good accordance with corrosive and catalytic experimental results.
- Adam, Mohamed Shaker S.,Soliman, Kamal A.,Abd El-Lateef, Hany M.
-
-
- Chiral cis-dioxidomolybdenum(VI) complexes with Schiff bases possessing two alkoxide groups: Synthesis, structure, spectroscopic studies and their catalytic activity in sulfoxidation and epoxidation
-
New chiral mononuclear cis-dioxidomolybdenum(VI) complexes, [MoO2(HL1-9)] and [MoO2(HL10)(CH3OH)], have been synthesized by the reaction of MoO2(acac)2 with tetradentate Schiff bases derived from various substituted salicylaldehydes and R(+)-3-amino-1,2-propanediol. All complexes have been characterized by elemental analysis, circular dichroism, electronic, IR and NMR (1H, 13C) spectroscopy. The molecular and crystal structure of [MoO2(HL10)(CH3OH)] elucidated by single-crystal X-ray diffraction revealed a six-coordinate distorted octahedral geometry and coordination of methanol molecule leaving one hydroxyl group uncoordinated. Surprisingly, NMR measurements made for [MoO2(HL1-9)] undoubtedly show that Schiff bases behave as dibasic tetradentate ONOO donor ligands and no solvent coordination has been observed. The catalytic activity studies have been also performed for all complexes in asymmetric sulfoxidation of thioanisole and epoxidation of styrene, cyclohexene and two monoterpenes, i.e. S(?)-limonene and (?)-α-pinene, using aqueous 30% H2O2 or tert-butyl hydroperoxide (TBHP) as the oxygen source.
- Karman, Marta,Romanowski, Grzegorz,Wera, Micha?
-
-
- SYNTHESIS AND APPLICATION OF CHIRAL SUBSTITUTED POLYVINYLPYRROLIDINONES
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Chiral polyvinylpyrrolidinone (CSPVP), complexes of CSPVP with a core species, such as a metallic nanocluster catalyst, and enantioselective oxidation reactions utilizing such complexes are disclosed. The CSPVP complexes can be used in asymmetric oxidation of diols, enantioselective oxidation of alkenes, and carbon-carbon bond forming reactions, for example. The CSPVP can also be complexed with biomolecules such as proteins, DNA, and RNA, and used as nanocarriers for siRNA or dsRNA delivery.
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-
Paragraph 0046; 0047; 0049
(2020/11/24)
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- Olefin reaction in the catalyst and the olefin production
-
PROBLEM TO BE SOLVED: To provide a catalyst for obtaining an olefin in high selectivity with a vicinal diol as a raw material.SOLUTION: A catalyst for olefination reaction for use in a reaction to produce an olefin by a reaction of a polyol, having two adjacent carbon atoms each having a hydroxy group, with hydrogen comprises: a carrier; at least one oxide selected from the group consisting of oxides of the group 6 elements and oxides of the group 7 elements supported on the carrier; and at least one metal selected from the group consisting of silver, iridium, and gold supported on the carrier.SELECTED DRAWING: None
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-
Paragraph 0147; 0149
(2020/10/31)
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- Selective hydrogenation of lignin-derived compounds under mild conditions
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A key challenge in the production of lignin-derived chemicals is to reduce the energy intensive processes used in their production. Here, we show that well-defined Rh nanoparticles dispersed in sub-micrometer size carbon hollow spheres, are able to hydrogenate lignin derived products under mild conditions (30 °C, 5 bar H2), in water. The optimum catalyst exhibits excellent selectivity and activity in the conversion of phenol to cyclohexanol and other related substrates including aryl ethers.
- Chen, Lu,Van Muyden, Antoine P.,Cui, Xinjiang,Laurenczy, Gabor,Dyson, Paul J.
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p. 3069 - 3073
(2020/06/17)
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- Flexible NiCo-based catalyst for direct hydrodeoxygenation of guaiacol to cyclohexanol
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The catalytic hydrodeoxygenation (HDO) of lignin-derived phenols is an important step for bio-oil upgrading. Herein, a novel HDO system was established in the presence of nitrogen, instead of traditional hydrogen. A series of CNT-supported Ni-based catalysts was prepared and introduced in the HDO of guaiacol and other lignin-derived phenolic compounds. The bimetallic NiCo/CNT catalysts exhibited better catalytic performance during the HDO reaction, in comparison with monometallic Ni/CNT and Co/CNT catalysts. Among these catalysts, the (15 + 5)% NiCo/CNT catalyst afforded the highest guaiacol conversion (up to 100%) with cyclohexanol as the main product in isopropanol. The effects of process parameters on guaiacol conversion and product distribution were studied in detail, finding that the presence of nitrogen could help to suppress the generation of byproducts, while the presence of hydrogen would facilitate the occurrence of side reactions. The HDO reaction of guaiacol occurred possibly in two consecutive steps: the demethoxylation of guaiacol to phenol and the further hydrogenation of the aromatic ring to cyclohexanol.
- Chen, Changzhou,Zhou, Minghao,Liu, Peng,Sharma, Brajendra K.,Jiang, Jianchun
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p. 18906 - 18916
(2020/11/18)
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- Catalytic oxidation of cyclohexene by supported gold nanoclusters synthesized in a two-liquid phases system containing eucalyptus essential oil
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Gold nanoclusters (d p = 6.3 nm, 3.5 wt% S) was contacted with aliquots of the Au-containing essential oil phase taken at 1, 3, 6 and 8 days of contact time between both phases. In this way, gold was immobilized on the support, ranging from 0.4 wt% for the 1-day sample, to 2.7 wt% in the 3-days material. UV–vis spectra show the presence of gold nanoclusters in these samples, but the surface plasmon resonance at 520 cm?1, characteristic of Au nanoparticles, was not detected save for the 3-days sample. 13C MAS NMR and TG evidence that the thiol groups of the support remain mostly unaltered for the 1-day sample, but oxidation to sulfonic acid groups becomes apparent for contact time > 3 days, and reaches nearly 60 % of the total sulphur species after 8 days of contact time as estimated from XPS analysis. The Au-SH-bearing catalyst is inactive for cyclohexene oxidation with molecular oxygen in liquid phase, but those having sulfonic groups are active and selective for its allylic oxidation. It has been found for the 8-day catalyst that the gold nanoclusters partially evolve spontaneously in the reaction medium to form gold nanoparticles, and this agglomeration process parallels the increase in catalyst activity.
- Agúndez, J.,Ares, C.,Márquez-álvarez, C.,Pérez-Pariente, J.
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- H2O2-based selective oxidations by divanadium-substituted polyoxotungstate supported on nitrogen-doped carbon nanomaterials
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In this work, we present a new methodology for the preparation of highly active, selective, leaching-tolerant and recyclable catalysts on the basis of polyoxometalates (POM) and nitrogen-doped carbon nanomaterials. A divanadium-substituted γ-Keggin phosphotungstate [γ-PW10O38V2(μ-O)(μ?OH)]4? (PV2), was immobilized on two types of supports – N-doped carbon nanofibers (N-CNFs) having herring-bone packing of graphite layers and bamboo-like N-doped carbon nanotubes (N-CNTs). Two series of catalysts have been prepared and characterized by elemental analysis, N2 adsorption, TEM, XPS and FTIR techniques. Their catalytic performance was assessed in the liquid-phase selective oxidation of two representative organic substrates, 2,3,6-trimethylphenol and cyclohexene, with aqueous H2O2 as the green oxidant. The presence of nitrogen in the supports ensures strong binding and quasi-molecular dispersion of POM on the carbon surface, which is crucial for the catalytic performance and catalyst stability. The catalysts reveal truly heterogeneous nature of the catalysis and can be easily recovered and reused without loss of the catalytic performance. The morphology of the support has a significant impact on the catalytic performance: the supported PV2 catalysts prepared using N-CNTs are more active and, in general, more selective than the catalysts prepared with N-CNFs.
- Evtushok, Vasiliy Yu.,Podyacheva, Olga Yu.,Suboch, Arina N.,Maksimchuk, Nataliya V.,Stonkus, Olga A.,Kibis, Lidiya S.,Kholdeeva, Oxana A.
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p. 196 - 203
(2019/04/03)
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- Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual-Functional Ruthenium/Montmorillonite
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Cleavage of ether bonds is a crucial but challenging step for lignin valorization. To efficiently realize this transformation, the development of robust catalysts or catalytic systems is required. In this study, montmorillonite (MMT)-supported Ru (denoted as Ru/MMT) is fabricated as a dual-functional heterogeneous catalyst to cleave various types of ether bonds through transfer hydrogenolysis without using any additional acids or bases. The prepared Ru/MMT material is found to efficiently catalyze the cleavage of various lignin models and lignin-derived phenols; cyclohexanes (fuels) and cyclohexanols (key intermediates) are the main products. The synergistic effect between electron-enriched Ru and the acidic sites on MMT contributes to the excellent performance of Ru/MMT. Systematic studies reveal that the reaction proceeds through two possible reaction pathways, including the direct cleavage of ether bonds and the formation of intermediates with one hydrogenated benzene ring, for all examined types of ether bonds, namely, 4-O-5, α-O-4, and β-O-4.
- Xue, Zhimin,Yu, Haitao,He, Jing,Zhang, Yibin,Lan, Xue,Liu, Rundong,Zhang, Luyao,Mu, Tiancheng
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p. 4579 - 4586
(2020/06/21)
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- Erbium-Catalyzed Regioselective Isomerization-Cobalt-Catalyzed Transfer Hydrogenation Sequence for the Synthesis of Anti-Markovnikov Alcohols from Epoxides under Mild Conditions
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Herein, we report an efficient isomerization-transfer hydrogenation reaction sequence based on a cobalt pincer catalyst (1 mol %), which allows the synthesis of a series of anti-Markovnikov alcohols from terminal and internal epoxides under mild reaction conditions (≤55 °C, 8 h) at low catalyst loading. The reaction proceeds by Lewis acid (3 mol % Er(OTf)3)-catalyzed epoxide isomerization and subsequent cobalt-catalyzed transfer hydrogenation using ammonia borane as the hydrogen source. The general applicability of this methodology is highlighted by the synthesis of 43 alcohols from epoxides. A variety of terminal (23 examples) and 1,2-disubstituted internal epoxides (14 examples) bearing different functional groups are converted to the desired anti-Markovnikov alcohols in excellent selectivity and yields of up to 98%. For selected examples, it is shown that the reaction can be performed on a preparative scale up to 50 mmol. Notably, the isomerization step proceeds via the most stable carbocation. Thus, the regiochemistry is controlled by stereoelectronic effects. As a result, in some cases, rearrangement of the carbon framework is observed when tri-and tetra-substituted epoxides (6 examples) are converted. A variety of functional groups are tolerated under the reaction conditions even though aldehydes and ketones are also reduced to the respective alcohols under the reaction conditions. Mechanistic studies and control experiments were used to investigate the role of the Lewis acid in the reaction. Besides acting as the catalyst for the epoxide isomerization, the Lewis acid was found to facilitate the dehydrogenation of the hydrogen donor, which enhances the rate of the transfer hydrogenation step. These experiments additionally indicate the direct transfer of hydrogen from the amine borane in the reduction step.
- Liu, Xin,Longwitz, Lars,Spiegelberg, Brian,T?njes, Jan,Beweries, Torsten,Werner, Thomas
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p. 13659 - 13667
(2020/11/30)
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- Multiple Mechanisms Mapped in Aryl Alkyl Ether Cleavage via Aqueous Electrocatalytic Hydrogenation over Skeletal Nickel
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We present here detailed mechanistic studies of electrocatalytic hydrogenation (ECH) in aqueous solution over skeletal nickel cathodes to probe the various paths of reductive catalytic C-O bond cleavage among functionalized aryl ethers relevant to energy science. Heterogeneous catalytic hydrogenolysis of aryl ethers is important both in hydrodeoxygenation of fossil fuels and in upgrading of lignin from biomass. The presence or absence of simple functionalities such as carbonyl, hydroxyl, methyl, or methoxyl groups is known to cause dramatic shifts in reactivity and cleavage selectivity between sp3 C-O and sp2 C-O bonds. Specifically, reported hydrogenolysis studies with Ni and other catalysts have hinted at different cleavage mechanisms for the C-O ether bonds in α-keto and α-hydroxy β-O-4 type aryl ether linkages of lignin. Our new rate, selectivity, and isotopic labeling results from ECH reactions confirm that these aryl ethers undergo C-O cleavage via distinct paths. For the simple 2-phenoxy-1-phenylethane or its alcohol congener, 2-phenoxy-1-phenylethanol, the benzylic site is activated via Ni C-H insertion, followed by beta elimination of the phenoxide leaving group. But in the case of the ketone, 2-phenoxyacetophenone, the polarized carbonyl πsystem apparently binds directly with the electron rich Ni cathode surface without breaking the aromaticity of the neighboring phenyl ring, leading to rapid cleavage. Substituent steric and electronic perturbations across a broad range of β-O-4 type ethers create a hierarchy of cleavage rates that supports these mechanistic ideas while offering guidance to allow rational design of the catalytic method. On the basis of the new insights, the usage of cosolvent acetone is shown to enable control of product selectivity.
- Hegg, Eric L.,Jackson, James E.,Klinger, Grace E.,Saffron, Christopher M.,Zhou, Yuting
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supporting information
p. 4037 - 4050
(2020/03/10)
-
- A hydrogen-bonded assembly of cucurbit[6]uril and [MoO2Cl2(H2O)2] with catalytic efficacy for the one-pot conversion of olefins to alkoxy products
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The reaction of the macrocyclic cavitand cucurbit[6]uril (CB[6]) and the diaqua complex [MoO2Cl2(H2O)2] in hydrochloric acid solution gave a water insoluble supramolecular compound with the general composition 2[MoO2Cl2(H2O)2]·CB[6]·xH2O·yHCl·z(CH3COCH3) (2). Single crystal X-ray diffraction (XRD) analysis revealed the presence of barrel-shape supramolecular entities, {CB[6]·10(H2O)}, aligned in layers which are shifted relative to adjacent layers to form a brick-like pattern. The CB[6]/water hydrogen-bonded entities further engage in intermolecular interactions with water, HCl and [MoO2Cl2(H2O)2] molecules to form a three-dimensional (3D) framework. Compound 2 was characterised by thermogravimetric analysis (TGA), IR and Raman vibrational spectroscopy, and 13C{1H} CP MAS NMR. The reference complex [MoO2Cl2(H2O)2]·(diglyme)2 (1) and compound 2 were studied for the oxidative catalytic conversion of olefins (cis-cyclooctene, cyclohexene and styrene) with aqueous H2O2 as oxidant. Using alcohols as solvents, 2 was employed in a one-pot two-stage strategy for converting olefins to alkoxy products, which involves oxidation (with H2O2) and acid chemistry. Mechanistic studies were carried out using different intermediates as substrates, and the type of solvent and substrate scope were investigated. The results demonstrated the ability of the CB[6]/MoVI supramolecular adduct to function as an acid-oxidation multifunctional catalyst, and its recovery and reuse via relatively simple procedures.
- Nogueira, Lucie S.,Antunes, Margarida M.,Gomes, Ana C.,Cunha-Silva, Luís,Pillinger, Martyn,Lopes, André D.,Valente, Anabela A.,Gon?alves, Isabel S.
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p. 11508 - 11519
(2019/08/07)
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- Demethoxylation of hydrogenated derivatives of guaiacol without external hydrogen over platinum catalyst
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Selective deoxygenation of 2-methoxycyclohexanone, one of the hydrogenated by-products in guaiacol hydrodeoxygenation, to phenol, cyclohexanone and cyclohexanol was investigated over carbon supported noble metal catalysts without external H2. Pt/C exhibited the best performance and the yield of target products reached 48% in water solvent at 493 K. This system can be applied to demethoxylation of 2-methoxycyclohexanol (49% yield). Demethoxylation of guaiacol is also possible under 0.1 MPa of H2 (46% yield). The yield of the target demethoxylation products was strongly dependent on the catalyst amount; too much catalyst decreased the yield due to the over-reaction, while the reaction stopped before total conversion of intermediates when the catalyst amount was too small. Fresh Pt/C catalyst has activity in hydrodeoxygenation of the target products and the reusability test showed deactivation of Pt/C during reaction, suggesting that deactivation at appropriate reaction progress controlled by catalyst amount is a key to good yield of the target products. In contrast to other noble metal catalysts, Pt/C has activity in both dehydrogenation of cyclohexane ring and hydrogenolysis of C–O bond, both of which contributed to the conversion of 2-methoxycyclohexanone to target demethoxylation products, according to the reactions of cyclohexanone and cyclohexanol as model substrates.
- Miyagawa, Akari,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
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-
- Influence of the channel size of isostructural 3d-4f MOFs on the catalytic aerobic oxidation of cycloalkenes
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The present work reports a new group of heterogeneous catalysts with a 3D structure, CuLnIDA, {[Cu3Ln2(IDA)6]·8H2O} (Ln: LaIII, GdIII or YbIII), with an organic linker (H2IDA: iminodiacetic acid). Different sets of O2 pressure and time were used in order to obtain the optimal reaction conditions at 75 °C. The reaction was found to depend on the [aldehyde]/[substrate] ratio. The best results, with a conversion of 73% for CuLaIDA as the catalyst, were obtained for the smallest ratio of 0.2. Finally, the importance of the pore size was analysed by comparing the catalytic activity of the as formed catalyst with that of the thermally activated one. The conversion increased ca. 26-35% for the different catalysts when they were previously activated. In addition, the selectivity increased towards cyclohexenone. The use of molecular oxygen as the oxidizing agent in a system where an auxiliary solvent is not used, as the cyclohexene substrate and products play the role of a solvent, permitted us to generate a more friendly environmental system for the oxidation of cycloalkenes under mild conditions.
- Cancino, Patricio,Santiba?ez, Luis,Stevens, Christian,Fuentealba, Pablo,Audebrand, Nathalie,Aravena, Daniel,Torres, Julia,Martinez, Sebastian,Kremer, Carlos,Spodine, Evgenia
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p. 11057 - 11064
(2019/07/31)
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- Magnetically separable and reusable rGO/Fe3O4 nanocomposites for the selective liquid phase oxidation of cyclohexene to 1,2-cyclohexane diol
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A series of magnetically separable rGO/Fe3O4 nanocomposites with various amounts of graphene oxide were successfully prepared by a simple ultrasonication assisted precipitation combined with a solvothermal method and their catalytic activity was evaluated for the selective liquid phase oxidation of cyclohexene using hydrogen peroxide as a green oxidant. The prepared materials were characterized using XRD, FTIR, FESEM, TEM, HRTEM, BET/BJH, XPS and VSM analysis. The presence of well crystallized Fe3O4 as the active iron species was seen in the crystal studies of the nanocomposites. The electron microscopy analysis indicated the fine surface dispersion of spherical Fe3O4 nanoparticles on the thin surface layers of partially-reduced graphene oxide (rGO) nanosheets. The decoration of Fe3O4 nanospheres on thin rGO layers was clearly observable in all of the nanocomposites. The XPS analysis was performed to evaluate the chemical states of the elements present in the samples. The surface area of the nanocomposites was increased significantly by increasing the amount of GO and the pore structures were effectively tuned by the amount of rGO in the nanocomposites. The magnetic saturation values of the nanocomposites were found to be sufficient for their efficient magnetic separation. The catalytic activity results show that the cyclohexene conversion reached 75.3% with a highest 1,2-cyclohexane diol selectivity of 81% over 5% rGO incorporated nanocomposite using H2O2 as the oxidant and acetonitrile as the solvent at 70 °C for 6 h. The reaction conditions were further optimized by changing the variables and a possible reaction mechanism was proposed. The enhanced catalytic activity of the nanocomposites for cyclohexene oxidation could be attributed to the fast accomplishment of the Fe2+/Fe3+ redox cycle in the composites due the sacrificial role of rGO and its synergistic effect with Fe3O4, originating from the conjugated network of π-electrons in its surface structure. The rapid and easy separation of the magnetic nanocomposites from the reaction mixture using an external magnet makes the present catalysts highly efficient for the reaction. Moreover, the catalyst retained its activity for five repeated runs without any drastic drop in the reactant conversion and product selectivity.
- Pudukudy, Manoj,Jia, Qingming,Dong, Yanan,Yue, Zhongxiao,Shan, Shaoyun
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p. 32517 - 32534
(2019/10/28)
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- Polymer immobilized tantalum(v)-amino acid complexes as selective and recyclable heterogeneous catalysts for oxidation of olefins and sulfides with aqueous H2O2
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Polymer supported heterogeneous peroxotantalum(v) catalysts were prepared by anchoring Ta(v)-diperoxo species to chloromethylated poly(styrene-divinylbenzene) resin functionalized with amino acids asparagine (l-Asn) and arginine (l-Arg). The structurally well-defined catalysts, [Ta(O2)2(L)2]--MR, [L = asparagine (catalyst 1) or arginine (catalyst 2) and MR = Merrifield resin], were comprehensively characterized by elemental analysis (CHN, ICP-OES, energy dispersive X-ray spectroscopy), spectral studies (FT-IR, Raman, 13C NMR, diffuse reflectance UV-vis and XPS), SEM, XRD, Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TGA). The supported peroxotantalum (pTa) compounds displayed excellent catalytic performance in epoxidation of alkenes with 30% H2O2, under solvent free reaction conditions. Styrene was epoxidized with >99% selectivity with the highest TOF of 1040 h-1 obtained within 30 min reaction time, whereas the TOF for norbornene epoxidation was 2000 h-1 within 1 h with >95% epoxide selectivity. Furthermore, the immobilized catalysts facilitated chemoselective oxidation of a broad range of organic sulfides to the desired sulfoxides with H2O2 in methanol, under mild reaction conditions. The oxidations proceeded with a high H2O2 efficiency percentage and are amenable to ready scalability. The heterogeneous catalysts could be easily recovered and reused for several consecutive catalytic cycles with undiminished activity/selectivity profiles in all cases. The developed catalytic strategies are operationally simple and, being free from halogenated solvent or any other toxic auxiliaries, environmentally clean.
- Saikia, Gangutri,Ahmed, Kabirun,Rajkhowa, Chandrasee,Sharma, Mitu,Talukdar, Hiya,Islam, Nashreen S.
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supporting information
p. 17251 - 17266
(2019/11/20)
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- Organic salts and merrifield resin supported [PM12O40]3? (M = Mo or W) as catalysts for adipic acid synthesis
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Adipic acid (AA) was obtained by catalyzed oxidation of cyclohexene, epoxycyclohexane, or cyclohexanediol under organic solvent-free conditions using aqueous hydrogen peroxide (30%) as an oxidizing agent and molybdenum- or tungsten-based Keggin polyoxometalates (POMs) surrounded by organic cations or ionically supported on functionalized Merrifield resins. Operating under these environmentally friendly, greener conditions and with low catalyst loading (0.025% for the molecular salts and 0.001–0.007% for the supported POMs), AA could be produced in interesting yields.
- Pisk, Jana,Agustin, Dominique,Poli, Rinaldo
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- OXIDATIVE CLEAVAGE OF OLEFINS, EPOXIDES AND ALCOHOLS
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Provided is a process for producing a compound I comprising at least one functional group chosen in the group consisting of epoxy group, hydroxyl group and carbonyl group and by reacting a compound J comprising at least one functional group chosen in the group consisting of alkenyl group, epoxy group and hydroxyl group with an an oxidant in the presence of solid amphiphilic catalytic particles A and solid amphiphilic catalytic particles B.
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-
Page/Page column 23
(2019/02/06)
-
- METHOD FOR PRODUCING 1,2-CYCLOHEXANEDIOL
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PROBLEM TO BE SOLVED: To provide a method for producing 1,2-cyclohexanediol with high selectivity. SOLUTION: A method for producing 1,2-cyclohexanediol has the step of reacting cyclohexene oxide with water, in the presence of a catalyst containing intermediate-pore diameter zeolite with an external surface acid point being deactivated. SELECTED DRAWING: None COPYRIGHT: (C)2019,JPO&INPIT
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-
Paragraph 0037-0048
(2019/08/13)
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- Carboxylate ionic liquid as well as preparation method and application thereof
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The invention provides carboxylate ionic liquid as well as a preparation method and application thereof. According to the carboxylate ionic liquid provided by the invention, an imidazole group or a pyridine group is introduced into the cationic part of the carboxylate ionic liquid and a carboxylic acid group is introduced into the anionic part of the carboxylate ionic liquid; and the ionic liquidcatalyst provided by the invention is simple and convenient in synthesis route, high in yield and easy to recover. Anion carboxylate radical in the carboxylate ionic liquid provided by the invention serves as an active site, so that synthesis of diol can be realized through high-efficiency and high-selectivity catalysis of hydration reaction of epoxy compounds under the condition of not adding other catalysts.
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-
Paragraph 0171-0173
(2019/10/23)
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- Epoxidation of cyclohexene with H2O2 over efficient water-tolerant heterogeneous catalysts composed of mono-substituted phosphotungstic acid on co-functionalized SBA-15
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A series of Keggin-type heteropolyacid-based heterogeneous catalysts (Co-/Fe-/Cu-POM-octyl-NH3-SBA-15) were synthesized via immobilized transition metal mono- substituted phosphotungstic acids (Co-/Fe-/Cu-POM) on octyl-amino-co-functionalized mesoporous silica SBA-15 (octyl-NH2-SBA-15). Characterization results indicated that Co-/Fe-/Cu-POM units were highly dispersed in mesochannels of SBA-15, and both types of Br?nsted and Lewis acid sites existed in Co-/Fe-/Cu-POM-octyl-NH3-SBA-15 catalysts. Co-POM-octyl-NH3-SBA-15 catalyst showed excellent catalytic performance in H2O2-mediated cyclohexene epoxidation with 83.8% of cyclohexene conversion, 92.8% of cyclohexene oxide selectivity, and 98/2 of epoxidation/allylic oxidation selectivity. The order of catalytic activity was Co-POM-octyl-NH3-SBA-15?>?Fe-POM-octyl-NH3-SBA-15?>?Cu-POM-octyl-NH3-SBA-15. In order to obtain insights into the role of -octyl moieties during catalysis, an octyl-free catalyst (Co-POM-NH3-SBA-15) was also synthesized. In comparison with Co-POM-NH3-SBA-15, Co-POM-octyl-NH3-SBA-15 showed enhanced catalytic properties (viz. activity and selectivity) in cyclohexene epoxidation. Strong chemical bonding between -NH3 + anchored on the surface of SBA-15 and heteropolyanions resulted in excellent stability of Co-POM-octyl-NH3-SBA-15 catalyst, and it could be reused six times without considerable loss of activity.
- Jin, Manman,Niu, Qingtao,Guo, Zhenmei,Lv, Zhiguo
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-
- Well-confined polyoxometalate-ionic liquid in silicic framework for environmentally friendly asymmetric di-hydroxylation of olefins
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Chiral 1,2-diols with a high yield could be directly prepared from asymmetric di-hydroxylation of olefins via an eco-friendly and enduring catalyst, in which abundant "chiral pools" of polyoxometalate-ionic liquid were target-designed into the silicic framework (POM-ILS) and well stabilized in aqueous media.
- Liang, Dong,Wang, Yan,Wang, Sifan,Song, Chengkun,Shi, Yonghe,Liu, Qinghao,Zhu, Hailin,Li, Xia,Liu, Laishuan,Zhu, Na
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p. 6102 - 6106
(2019/03/12)
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- Aromatic Donor-Acceptor Interaction-Based Co(III)-salen Self-Assemblies and Their Applications in Asymmetric Ring Opening of Epoxides
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Aromatic donor-acceptor interaction as the driving force to assemble cooperative catalysts is described. Pyrene/naphthalenediimide functionalized Co(III)-salen complexes self-assembled into bimetallic catalysts through aromatic donor-acceptor interactions and showed high catalytic activity and selectivity in the asymmetric ring opening of various epoxides. Control experiments, nuclear magnetic resonance (NMR) spectroscopy titrations, mass spectrometry measurement, and X-ray crystal structure analysis confirmed that the catalysts assembled based on the aromatic donor-acceptor interaction, which can be a valuable noncovalent interaction in supramolecular catalyst development.
- Liang, Jian,Soucie, Luke N.,Blechschmidt, Daniel R.,Yoder, Aaron,Gustafson, Addie,Liu, Yu
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supporting information
p. 513 - 518
(2019/01/14)
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- Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
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Cleavage of aromatic ether bonds is a key step for lignin valorization, and the development of novel heterogeneous catalysts with high activity is crucial. Herein, bifunctional Ru/hydroxyapatite has been prepared via ion exchange and subsequent reduction. The obtained Ru/hydroxyapatite could efficiently catalyze the cleavage of various compounds containing aromatic ether bonds via transfer hydrogenolysis without additional bases. Systematic studies indicated that the basic nature of hydroxyapatite and electron-enriched Ru sites resulted in the high activity of the catalyst. A mechanism study revealed that the direct cleavage of aromatic ether bonds was the main reaction pathway.
- Hua, Manli,Song, Jinliang,Xie, Chao,Wu, Haoran,Hu, Yue,Huang, Xin,Han, Buxing
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p. 5073 - 5079
(2019/09/30)
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- A Nanospherical Mesoporous Ruthenium-Containing Polymer as a Guaiacol Hydrogenation Catalyst
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Abstract: A hybrid catalyst is synthesized using ruthenium nanoparticles deposited on a nanospherical mesoporous polymer. Catalytic properties are studied in guaiacol hydrogenation at a temperature of 200–250°С and a hydrogen pressure of 5.0 MPa. Effect of solvent and catalytic additives on the reaction is investigated. It is shown that the synthesized catalyst exhibits the highest activity in guaiacol hydrodeoxygenation in the two-phase system water/n-dodecane and when the reaction is carried out in the presence of scandium triflate.
- Boronoev,Shakirov,Ignat’eva,Maximov,Karakhanov
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p. 1300 - 1306
(2020/01/02)
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- A Bimetallic Pure Inorganic Framework for Highly Efficient and Selective Photocatalytic Oxidation of Cyclohexene to 2-Cyclohexen-1-ol
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Abstract: The highly efficient and selective photocatalytic oxidation of cyclohexene with molecular oxygen under mild conditions is an important objective in chemical synthesis. In this work, a pure inorganic framework CoMo was self-assembly prepared under solvothermal conditions by incorporating simple MoO42?, cobalt (II) ion. The catalyst CoMo was well characterized by infrared spectroscopy (FTIR), nitrogen adsorption–desorption, powder X-ray diffraction (XRD), scanning electron spectroscopy (SEM), and X-ray photoelectron spectroscopy (XPS) methods. It displayed high efficiency and selectivity in the photocatalytic oxidation of cyclohexene to 2-cyclohexen-1-ol in O2 atmosphere. The influence of solvents, oxidants, pressure of oxygen, reaction temperature, light source and time on the reaction was investigated. More interestingly, the selectivity of the reaction in 4-ethyltoluene was much higher than that in other solvents. Graphic Abstract: [Figure not available: see fulltext.].
- Shi, Xiaoyun,Shi, Zhuolin,Niu, Guiqin,Si, Chen,Han, Qiuxia,Zhang, Jingjing
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p. 3048 - 3057
(2019/06/17)
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- High surface area, nanostructured boehmite and alumina catalysts: Synthesis and application in the sustainable epoxidation of alkenes
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We report a new, straightforward and inexpensive sol-gel route to prepare boehmite nanorods [γ-AlO(OH)-NR] with an average length of 23 nm ± 3 nm, an average diameter of 2 nm ± 0.3 nm and a high specific surface area of 448 m2/g, as evidenced by TEM and N2-physisorption, respectively. The boehmite was converted to γ-alumina with preserved nanorod morphology (γ-Al2O3-NR) and high surface area upon calcination either at 400 or 600 °C. These nanostructured materials are active and selective heterogeneous catalysts for the epoxidation of alkenes with the environmentally friendly H2O2. The best catalyst, γ-Al2O3-NR-400, showed to be versatile in the scope of alkenes that could be converted selectively to their epoxide and displayed enhanced reusability compared to previously reported alumina catalysts. Furthermore, the catalytic performance of the material was enhanced by optimising the reaction conditions such as the solvent and the type of hydrogen peroxide source. Under the optimised reaction conditions, the γ-Al2O3-NR-400 catalyst displayed 58% cyclooctene oxide yield after 4 h of reaction at 80 °C with full selectivity towards the epoxide product. The correlation between the catalytic activity of these materials and their physicochemical properties such as surface area, hydrophilicity and number and type of acid sites was critically discussed based on a detailed characterisation study.
- Lueangchaichaweng, Warunee,Singh, Bhawan,Mandelli, Dalmo,Carvalho, Wagner A.,Fiorilli, Sonia,Pescarmona, Paolo P.
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p. 180 - 187
(2019/01/04)
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- Ru subnanoparticles on N-doped carbon layer coated SBA-15 as efficient Catalysts for arene hydrogenation
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The N-doped carbon layer coated SBA-15 support has been accomplished via a pyrolysis process. The ultra-low loading Ru nanoparticles (ca. 0.1 wt.%) was incorporated into the support by impregnation and the sequential reduction. The images of HAADF-STEM revealed that the Ru particles with sub-1-nm size (0.2-0.7 nm) were uniformly dispersed on the support. The ultrafine Ru particles displayed the excellent activity for the hydrogenation of olefins, arenes, phenol derivatives and heteroarenes in aqueous phase. The aliphatic or alicyclic compounds were produced selectively without the hydrogenolysis of C–O and C–N bonds. The high turnover frequency (TOF) values can reach up to 10,000 h?1. Notably, the activity of these catalysts improved dramatically with decreasing the sizes of Ru particles. Meanwhile, the N-doped carbon layer coating endowed the high stability of the Ru catalysts and prevented the leaching of the Ru species owning to the strong interaction between doped-N atoms and the ultrafine Ru particles. Overall, this work provides a highly attractive strategy to construct the supported sub-1-nm Ru particles utilized for the aqueous hydrogenation.
- Qian, Wei,Lin, Lina,Qiao, Yunxiang,Zhao,Xu, Zichen,Gong, Honghui,Li,Chen,Huang, Rong,Hou, Zhenshan
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- Oxy-functionalization of olefins with neat and heterogenized binuclear V(IV)O and Fe(II)complexes: Effect of steric hindrance on product selectivity and output in homogeneous and heterogeneous phase
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Neat {[VO(sal2bz)]2; [Fe(sal2bz)(H2O)2]2·2H2O} and zeolite-Y immobilized {[VO(sal2bz)]2-Y; [Fe(sal2bz)(H2O)2]2-Y} binuclear complexes have been prepared and characterized by spectroscopic techniques (IR, UV–vis), elemental analyses (CHN, ICP-OES), thermal study (TGA), scanning electron micrograph (SEM), adsorption study (BET)and X-ray diffraction (XRD)patterns. Neat (homogeneous)and immobilized (heterogeneous)complexes were employed as catalysts in the oxidation of olefins, namely, cyclohexene, limonene and α-pinene in the presence of 30% hydrogen peroxide. 100% conversion of cyclohexene and α-pinene was obtained while limonene was oxidized up to 90%. Homogeneous catalysts showed highly selective result as neat [VO(sal2bz)]2 complex has provided 87% cyclohexane-1,2-diol and neat [Fe(sal2bz)(H2O)2]2·2H2O complex has provided 79% verbenone in oxidation of cyclohexene and α-pinene, respectively. We have observed that due to steric hindrance, formation of olefinic oxidation products increases on moving from α-pinene to limonene and limonene to cyclohexene. Additionally. recovered heterogeneous catalysts showed intact results up to two consecutive runs. Probable catalytic mechanism has been proposed for oxidation of cyclohexene.
- Parmar, Digvijaysinh K.,Butani, Pinal M.,Thumar, Niraj J.,Jasani, Pinal M.,Padaliya, Ravi V.,Sandhiya, Paba R.,Nakum, Haresh D.,Khan, Md. Nasim,Makwana, Dipak
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