- Fabrication of hierarchical composite microspheres of copper-doped Fe3O4@P4VP@ZIF-8 and their application in aerobic oxidation
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Novel hierarchical magnetic composite microspheres of copper-doped Fe3O4@poly(4-vinylpyridine-co-divinylbenzene)@ZIF-8 (Cu-FPZ, Cu stands for copper doped) were successfully fabricated. The core-shell Fe3O4(PAA)@P4VP magnetic microspheres were first synthesized by a polymerization approach, in which the 4-vinylpyridine (4-VP) monomer interacted with a-COOH group of poly(acrylic acid) modified Fe3O4 by means of a hydrogen-bond interaction. Then Zn2+ was adsorbed on the surface of the P4VP shell, followed by the formation of a ZIF-8 porous shell with 2-methylimidazolate. Finally, nearly 5.45 wt% of copper content was incorporated with the ZIF-8 framework to form a magnetic core-shell copper-doped Fe3O4@P4VP@ZIF-8. The obtained copper-doped Fe3O4@P4VP@ZIF-8 catalyst was applied in the selective oxidation of alcohols and epoxidation of olefins using molecular oxygen as the oxidant. The results demonstrated that the magnetic core-shell copper-doped Fe3O4@P4VP@ZIF-8 catalyst showed better catalytic activity with significantly improved turnover number and turnover frequency (up to 8.25 h-1) than other copper MOFs. Furthermore, this heterogeneous catalyst could be cycled at least 15 times without significant loss of activity.
- Hou, Junying,Luan, Yi,Yu, Jie,Qi, Yue,Wang, Ge,Lu, Yunfeng
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- Binuclear molybdenum Schiff-base complex: An efficient catalyst for the epoxidation of alkenes
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Dimolybdenum Schiff-base complex (DMSBC) which contain O,N-bidentate ligand was synthesized and characterized. The complex can be used as a promising catalyst in the epoxidation of olefins with tert-butyl-hydroperoxide (TBHP) as oxidant. The catalytic activity of the DMSBC was optimized by adjusting various parameters. Epoxidation of olefins by DMSBC indicated that the catalyst exhibited superb catalytic activity with high conversions up to 99.6%, high selectivity up to 100%, and high turnover frequency (TOF) of 208 h?1. Kinetic analysis provided that epoxidation of cyclooctene by DMSBC possessed moderate activation energy (95.3 ± 2 kJ·mol?1). Furthermore, the calculated pre-exponential factor (A) proved that strong collisions probability take place in the reaction. Additionally, the recycle experiments demonstrated that DMSBC could be recovered and repeatedly applied.
- Guo, Yingxiong,Xiao, Longqiang,Li, Pan,Zou, Wenhong,Zhang, Wenzhe,Hou, Linxi
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- Catalytic hydrocarbon oxygenation by a dinuclear ruthenium(II) complex with molecular oxygen
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A bis-μ-chloro Ru(II) dimer with tris(2-pyridylmethyl)amine (TPA) exhibited catalytic oxygenation of alkenes and cooxygenation of alkanes in the presence of cyclohexene with molecular oxygen (latm) at room temperature without reducing reagents; reactions proceeded via a radical chain mechanism as a main pathway.
- Kojima, Takahiko,Matsuda, Yoshihisa
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- Hydrogen-bond-supported 3D networks: Two different polymeric structures featuring chlorine atoms as ligands and as anions and investigations as epoxide catalysts
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Two novel hydrogen-bonded network polymers, [MoO2Cl 2-(H2O)2]2[4,4′-H 2bipy]2+·2Cl- (1) and [MoO 2Cl4]2-[4,4′-H2-bipy] sup
- Luan, Yi,Wang, Ge,Luck, Rudy L.,Wang, Yingnan,Xiao, Han,Ding, Hangjun
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- A New Active Intermediate in Monooxygenations Catalyzed by Iron Porphyrin Complexes
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A new type of high-valent oxoiron porphyrin (3b) has been prepared by the reaction of FeIII(tdcpp) (1b) [tdcpp: 5, 10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin] with an oxidant such as p-nitroperbenzoic acid and pentafluoroiodosylbenzene at -
- Murakami, Tatsuya,Yamaguchi, Kazuya,Watanabe, Yoshihito,Morishima, Isao
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- Epoxidation of Alkenes with Iodosylbenzene catalysed by a Water-soluble Chromium(III) N,N'-Ethylene bis(salicylideneaminato) (salen) Complex using β-Cyclodextrin as a Phase Transfer Agent
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Addition of β-cyclodextrin as a phase-transfer agent resulted in an increase in yields and rates of epoxidation of alkenes with iodosylbenzene, catalysed by the water soluble complex Cl in water - methylene chloride.
- Ganeshpure, P. A.,Satish, S.
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- Halogenated tetraphenyl porphyrin; Iodosylbenzene an efficient catalytic system for olefin epoxidation
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Olefin epoxidation using o-phenyl and b-pyrrole substituted tetraphenyl porphyrin complexes of Fe(III) and Mn(III) as catalysts and yIodosylbenzene as oxidant was studied. Excellent yields of epoxide and secondary oxidation products were observed. Effect of pyridine, imadizole, sodium lauryl sulphate, and solvent variation was also studied. Effect of substituents on catalytic activity of the porphyrin complex is also explained. o-phenyl substituted complexes gave better yield of epoxide as compared to b-pyrrole substituted complexes.
- Aggrawal, Dau D.,Bhat, Daisy
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- Epoxidation of Alkenes Catalyzed by Iron(III) Schiff Base Chelates. A Monooxygenase Model
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Iron(III) Schiff base chelates Cl2 (1), Cl2 (2), and Cl (3), were synthesized, where (PA2ppd), (PA2mpd), and (PA2opd) are the Schiff bases derived from 2-pyridinecarbaldehyde (PA), and p-phenylenediamine (p
- Jacob, Mathew,Bhattacharya, Pabitra Krishna,Ganeshpure, Pralhad A.,Satish, Sheo,Sivaram, Swaminathan
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- Zirconium containing mesoporous silicas: New catalysts for oxidation reactions in the liquid phase
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Zirconium containing mesoporous silicas are synthesized using hexadecylamine as surfactant; the new materials show very interesting properties as catalysts in liquid-phase oxidations with H2O2 and alkyl peroxides.
- Tuel,Gontier,Teissier
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- Effective alkene epoxidation with dilute hydrogen peroxide on amorphous silica-supported titanium catalysts
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The use of amorphous silica-supported titanium catalysts in which the titanium ions display a chemical environment similar to that of Ti- substituted zeolites, afforded excellent activity in the epoxidation of terminal linear and bulky alkenes with dilute solutions of hydrogen peroxide.
- Capel-Sanchez,Campos-Martin,Fierro,De Frutos,Padilla Polo
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- A novel magnesium oxide supported polytitazane-tin tetrachloride catalyst for aerobic epoxidation of cycloalkenes under mild conditions
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A magnesium oxide supported polytitazane-tin tetrachloride complex is found to be a novel efficient catalyst for epoxidation of cycloalkenes with molecular oxygen with 1,4-dioxane as a co-reductant under mild conditions.
- Wang, Tie-Jun,Ma, Zhao-Hui,Yan, Yuan-Yong,Huang, Mei-Yu,Jiang, Ying-Yan
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- Liquid-phase oxidation of olefins with rare hydronium ion salt of dinuclear dioxido-vanadium(V) complexes and comparative catalytic studies with analogous copper complexes
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Homogeneous liquid-phase oxidation of a number of aromatic and aliphatic olefins was examined using dinuclear anionic vanadium dioxido complexes [(VO2)2(salLH)]? (1) and [(VO2)2(NsalLH)]? (2) and dinuclear copper complexes [(CuCl)2(salLH)]? (3) and [(CuCl)2(NsalLH)]? (4) (reaction of carbohydrazide with salicylaldehyde and 4-diethylamino salicylaldehyde afforded Schiff-base ligands [salLH4] and [NsalLH4], respectively). Anionic vanadium and copper complexes 1, 2, 3, and 4 were isolated in the form of their hydronium ion salt, which is rare. The molecular structure of the hydronium ion salt of anionic dinuclear vanadium dioxido complex [(VO2)2(salLH)]? (1) was established through single-crystal X-ray analysis. The chemical and structural properties were studied using Fourier transform infrared (FT-IR), ultraviolet–visible (UV–Vis), 1H and 13C nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), electron paramagnetic resonance (EPR) spectroscopy, and thermogravimetric analysis (TGA). In the presence of hydrogen peroxide, both dinuclear vanadium dioxido complexes were applied for the oxidation of a series of aromatic and aliphatic alkenes. High catalytic activity and efficiency were achieved using catalysts 1 and 2 in the oxidation of olefins. Alkenes with electron-donating groups make the oxidation processes easy. Thus, in general, aromatic olefins show better substrate conversion in comparison to the aliphatic olefins. Under optimized reaction conditions, both copper catalysts 3 and 4 fail to compete with the activity shown by their vanadium counterparts. Irrespective of olefins, metal (vanadium or copper) complexes of the ligand [salLH4] (I) show better substrate conversion(%) compared with the metal complexes of the ligand [NsalLH4] (II).
- Maurya, Abhishek,Haldar, Chanchal
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- Formation of β-Ga2O3nanorings from metal-organic frameworks and their high catalytic activity for epoxidation of alkenes
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Here we report a novel synthesis of hollow high-quality β-Ga2O3 nanorings based on an interesting structural evolution from concave Ga-MOF nanodisks. The concave low-crystallinity nanodisks were constructed by non-classical crystallization with particle a
- Wang, Wei Ping,Song, Le Xin,Li, Yao,Teng, Yue,Xia, Juan,Wang, Fang,Liu, Nan Ning
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p. 349 - 357
(2021/01/14)
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- New Cu(II), Co(II) and Ni(II) azo-Schiff base complexes: Synthesis, characterization, catalytic oxidation of alkenes and DFT study
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Three new complexes with general formula of ML (M = Cu (1), Co (2), Ni (3)) containing an azo-Schiff base ligand (H2L) derived from 2,3-butanediamine and 4-(benzeneazo) salicylaldehyde were synthesized by template method. Characterization of the ligand and complexes were accomplished with FT-IR, UV–Vis, and 1H NMR. The catalytic activity of the complexes (1–3) were tested for the oxidation of various alkenes (cyclooctene, cyclohexene, styrene, α-methyl styrene, and norbornene) applying tert-butyl hydroperoxide (TBHP) as an oxidizing agent, and it was found that they were acceptable catalysts. Under the optimized reaction conditions, CuL complex displayed 94% conversion for the oxidation of cyclooctene, and CoL and NiL complexes exhibited 90 and 85% conversions for oxidizing α-methyl styrene, respectively. Based on our density functional computations, diffuse functions are compulsory in the basis set for geometry optimization of these systems. Therefore, the most stable structures and the vibrational frequencies were calculated at the M06-2X/6–311++G(d,p) level. By establishing the correlation between observed and calculated frequencies, the assignment of the vibrational modes was performed. Based on natural charge analysis (NAO), the back electron transfer from ML to the TBHP breaks the O–O bond and facilitates the formation of tert-butoxyl radicals.
- Lashanizadegan, Maryam,Asna Ashari, Hadiseh,Sarkheil, Marzieh,Anafcheh, Maryam,Jahangiry, Samira
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- A sustainable approach towards solventless organic oxidations catalyzed by polymer immobilized Nb(V)-peroxido compounds with H2O2 as oxidant
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New heterogeneous catalysts comprising of peroxidoniobium(V) complexes immobilized on amino acid grafted cross-linked poly(styrene-divinylbenzene) resin has been developed. Results of FTIR, Raman, NMR, XPS, XRD, EDX, SEM, BET, TGA, and elemental analysis confirmed the successful anchoring of triperoxidoniobium(V), [Nb(O2)3]? species to the host polymer via the pendant amino acid groups. The supported catalysts exhibited excellent performance in epoxidation of styrene and a range of cyclic and terpenic compounds under environmentally acceptable solvent-free condition, with aqueous H2O2 as oxidant. The catalytic protocols provided excellent conversion to the desired epoxide (up to 100%) with selectivity > 99%, TON as high as 1000, and high H2O2 utilization efficiency (92–97%). Moreover, the catalysts efficiently facilitated chemoselective solvent-free oxidation of a variety of thioethers to sulfones at room temperature. Simple operational strategy, easy recyclability for multiple reaction cycles with the consistent activity-selectivity profile are the additional significant attributes of the developed catalytic processes.
- Ahmed, Kabirun,Gogoi, Sandhya Rani,Islam, Nashreen S.,Saikia, Gangutri,Sultana, Sazida Yasmin,Talukdar, Hiya
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- Homogeneous catalytic oxidation of alkenes employing mononuclear vanadium complex with hydrogen peroxide
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Abstract: Homogeneous liquid-phase oxidation of alkenes (allylbenzene, cis-cyclooctene, 4-chlorostyrene, styrene, 2-norbornene, 1-methyl cyclohexene, indene, lemonine, and 1-hexene) were catalyzed by using vanadium complex [VO(hyap)(acac)2] in existence of H2O2. The complex [VO(hyap)(acac)2] was formed as a crystal by the reaction of [VO(acac)2] and 2-hydroxyacetophenone (hyap) in the presence of methanol by refluxing the reaction mixture. Various analytical and spectroscopic techniques, namely FTIR, ESI–MS, UV–Vis, single-crystal XRD, and EPR, were used to analyze and optimize the structure of the complexes. Graphic abstract: [Figure not available: see fulltext.].
- Maurya, Abhishek
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p. 3261 - 3269
(2020/07/14)
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- Growth of Cu-BTC MOFs on dendrimer-like porous silica nanospheres for the catalytic aerobic epoxidation of olefins
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The composition of metal-organic frameworks (MOFs) and porous carriers can be utilized for a variety of material applications. In this study, DPSNs@Cu-BTC nanocomposites are achieved utilizing Dendrimer-like Porous Silica Nanoparticles (DPSNs) as the support through a template-mediated self-assembly mechanism. The fabrication process is initiated from the controllable growth of Cu2O nanoparticles (NPs) in the center-radial porous channels of DPSNs, which forms DPSNs@Cu2O nanocomposites. Under the protection of DPSNs, the loaded Cu2O NPs gradually dissolved in the weak acid solution, thus providing copper ions to guide the formation and growth of Cu-BTC nanocrystals. Moreover, the Cu-BTC NPs were restricted in the center-radial porous channels of the DPSNs, thus resulting in small sizes and a uniform distribution. The formation of the DPSNs@Cu-BTC nanocomposites with adjustable amounts of Cu-BTC mainly depended on the amounts of Cu2O NPs loaded and the amount of organic ligands added. Furthermore, the nanocomposite exhibited high catalytic performance and good recyclability taking advantage of the uniform loading of small-sized Cu-BTC NPs in the accessible center-radial porous channels of the DPSNs. This new design of DPSNs@Cu-BTC provided a new approach for the synthesis of various MOF-based nanocomposites with improved performance.
- Zhou, Zihao,Li, Xiujuan,Wang, Yulin,Luan, Yi,Li, Xiaoyu,Du, Xin
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p. 14350 - 14357
(2020/09/21)
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- Synthesis of a new schiff base oxovanadium complex with melamine and 2-hydroxynaphtaldehyde on modified magnetic nanoparticles as catalyst for allyl alcohols and olefins epoxidation
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A new magnetically recoverable nanocatalyst designated as Fe3O4@SiO2@PTMS@Mel-Naph-VOcomplex was synthesize by covalent binding of a Schiff base ligand derived from melamine and 2-hydroxy1naphtaldehyde on the surface of silica coated iron oxide magnetic nanoparticles followed by complexation with VO (acac)2. Characterization of the prepared nanocatalyst was accomplished with FT-IR, XRD, SEM, HRTEM, VSM and atomic absorption techniques. It was found that the epoxidation of geraniol, trans-2-hexen-1-ol, 1-octen-3-ol, norbornene, and cyclooctene is highly selective, affording quantitative yields of the corresponding epoxides with tert-butyl hydroperoxide (TBHP) using Fe3O4@SiO2@Mel-Naph-VOcomplex as catalyst. High reaction yields, short reaction times, simple experimental and work up procedure, catalyst stability and excellent reusability even after five-cycles of usage in the case of geraniol are some advantages of this research.
- Farzaneh, Faezeh,Asgharpour, Zeinab
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- Acrylate compound for coatings, preparation method of acrylate compound, and coating comprising acrylate compound and application of coating
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The invention relates to an acrylate compound for coatings. The compound has a structure represented by a formula (I). The acrylate compound for coatings has lipophilic polycyclic aliphatic groups andhydrophilic hydroxyl groups at a same time and has high polymerization reaction activity. When the acrylate compound is used for a solvent-type acrylic coating, the coating layer shows relatively excellent weather resistance and wear resistance, high glossiness and fullness and the like. When the acrylate compound is used for a water-based acrylic coating, the hydrophilic hydroxyl groups and thelipophilic alicyclic groups of the compound show good solubility in an emulsion system, the polymerization activity is high, the monomer residue amount is low, and the coating after film forming showsexcellent weather resistance, water resistance, oil resistance, impact resistance, high glossiness and the like. The preparation method has the advantages that the technological process is simple, conditions are easy to control, side reactions are few, the raw material conversion rate of reactions is high, and purity of products is high.
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Paragraph 0081; 0083-0085
(2019/07/16)
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- Structural, Theoretical and Spectroscopic Characterisation of a Series of Novel Gold(I)-Norbornene Complexes Supported by Phenanthrolines: Effects of the Supporting Ligand
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A series of novel gold(I) alkene complexes of general formula [Au(N^N)(η2-nb)][PF6] [N^N = PHEN (1,10-phenanthroline), NCP (2,9-dimethyl-1,10-phenanthroline), 4,7-DMP (4,7-dimethyl-1,10-phenanthroline), TMP (3,4,7,8-tetramethyl-1,10-phenanthroline), BTP (4,7-diphenyl-1,10-phenanthroline) and BTC (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline); nb = norbornene] were synthesized by a novel synthetic pathway. The novel cationic gold(I)-norbornene complexes were fully characterized by 1H and 13C NMR spectroscopy and the crystal structure of three complexes was solved by single-crystal X-ray diffraction. The correlations between the nature and position of the substituents on the ancillary ligand and the spectroscopic and structural data highlight variations on the nature of the bonding. The combination of experimental and DFT data allowed to evaluate the extent of σ-donation and π back-donation in the bond with the olefin, suggesting that a fine interplay between electronic and steric effects on the ancillary ligand can affect the bond properties and structural features of the complexes.
- Cinellu, Maria A.,Arca, Massimiliano,Ortu, Fabrizio,Stoccoro, Sergio,Zucca, Antonio,Pintus, Anna,Maiore, Laura
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p. 4784 - 4795
(2019/11/26)
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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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- Epoxidation of Cyclooctene Using Water as the Oxygen Atom Source at Manganese Oxide Electrocatalysts
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Epoxides are useful intermediates for the manufacture of a diverse set of chemical products. Current routes of olefin epoxidation either involve hazardous reagents or generate stoichiometric side products, leading to challenges in separation and significant waste streams. Here, we demonstrate a sustainable and safe route to epoxidize olefin substrates using water as the oxygen atom source at room temperature and ambient pressure. Manganese oxide nanoparticles (NPs) are shown to catalyze cyclooctene epoxidation with Faradaic efficiencies above 30%. Isotopic studies and detailed product analysis reveal an overall reaction in which water and cyclooctene are converted to cyclooctene oxide and hydrogen. Electrokinetic studies provide insights into the mechanism of olefin epoxidation, including an approximate first-order dependence on the substrate and water and a rate-determining step which involves the first electron transfer. We demonstrate that this new route can also achieve a cyclooctene conversion of ～50% over 4 h.
- Jin, Kyoungsuk,Maalouf, Joseph H.,Lazouski, Nikifar,Corbin, Nathan,Yang, Dengtao,Manthiram, Karthish
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supporting information
p. 6413 - 6418
(2019/05/02)
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- Modification of Cu2+ into Zr-based metal–organic framework (MOF) with carboxylic units as an efficient heterogeneous catalyst for aerobic epoxidation of olefins
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A series of metal-organic framework (MOF) based catalysts for aerobic epoxidation were reported. A post-synthetic modification strategy using a solvothermal method enabled the incorporation of three different copper salts on a Zr-based MOF material UiO-66-(COOH)2; catalysts Cu@UiO-1, Cu@UiO-2 and Cu@UiO-3 were obtained. When analyzed by SEM and EDX, no impact of the post-synthetic modification on the core structure of the UiO-66-(COOH)2 framework was noticed. Studies showed Cu@UiO-1 to be the optimal catalyst for aerobic epoxidation thanks to its broad substrate scope, thermal stability, excellent recyclability. Observed catalytic properties are also better than those of previously reported copper catalysts.
- Zhao, Jian,Wang, Wenyu,Tang, Houliang,Ramella, Daniele,Luan, Yi
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- Cobalt immobilized on hydroxyapatite as a low-cost and highly effective heterogeneous catalyst for alkenes epoxidation under mild conditions
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Transition metal Co immobilized on hydroxyapatite with a loading of 0.05 wt% (denoted 0.05 wt% Co/HAP) could catalyze partial oxidation of cyclic alkenes, aromatic alkenes and aliphatic alkenes to yield epoxide products with excellent selectivity at 30 °C with O2 and iso-butyraldehyde as co-oxidant. The TOF value was as high as 6261 h?1 for epoxidation of cyclohexene. In addition, the prepared 0.05 wt% Co/HAP catalyst can be re-used at least 6 times without significant loss of catalytic activity and selectivity.
- Mekrattanachai, Pagasukon,Cao, Changyan,Li, Zhaohua,Li, Huining,Song, Weiguo
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p. 37303 - 37306
(2018/11/26)
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- Epoxidation of alkenes by an oxidovanadium(IV) tetradentate Schiff base complex as an efficient catalyst with tert-butyl hydroperoxide
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A new asymmetrical tetradentate N2O2Schiff base ligand was synthesized from 2-hydroxyacetophenon, 2-hydroxynaphthaldehyde and 1,2 phenylenediimine. The new oxidovanadium(IV) Schiff base complex, VIVOL (L?=?N-2-hydroxyacetophenon-N′-2-hydroxynaphthaldehyde-1,2 phenylenediimine), was prepared by reaction of Schiff base ligand with vanadyl acetylacetonate. The Schiff base ligand (L) and the oxidovanadium(IV) complex were characterized by spectroscopic methods. The crystal structure of the complex was determined by the single crystal X-ray analysis. The complex crystallized in the orthorhombic system, having one V4+ion coordinating in an approximately square pyramidal N2O3geometry by two azomethine N atoms and phenolic oxygens from Schiff base ligand in a square plane and one oxygen atom in an apical position. Electrochemical properties of the complex were examined by means of cyclic voltammetry. The catalytic activity of the oxidovanadium(IV) Schiff base complex was tested in the epoxidation of cyclooctene.
- Sedighipoor, Maryam,Kianfar, Ali Hossein,Mahmood, Wan Ahmad Kamil,Azarian, Mohammad Hossein
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p. 116 - 121
(2016/12/27)
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- Stable Copper Nanoparticle Photocatalysts for Selective Epoxidation of Alkenes with Visible Light
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Selective epoxidation of various alkenes with molecular oxygen (O2) under mild conditions is a longstanding challenge in achieving syntheses of epoxides. Cu-based catalysts have been found to be catalytically active for selective epoxidations. However, the application of copper nanoparticles (CuNPs) for photocatalyzed epoxidations is encumbered by the instability of CuNPs in air. Herein we report that CuNPs supported on titanium nitride (TiN) without additional stabilizers not only are stable in air but also can catalyze selective epoxidation of various alkenes with O2 or even air as a benign oxidant under light irradiation. CuNPs remain in the metallic state due to the significant charge transfer that occurs between CuNPs and TiN. The epoxidation is driven by visible light irradiation at moderate temperatures, achieving good to high yields and excellent selectivity. The photocatalytic process is applicable to the selective epoxidation of various alkenes. In this photocatalytic system, reactant alkenes chemically adsorb on CuNPs, forming Cu-alkene surface complexes, and light irradiation can activate the complexes for reaction. The cyclic ether solvent also plays a key role, reacting with O2 on the surface of CuNPs under light irradiation, yielding oxygen adatoms. The activated surface complexes react with the adatoms, yielding the corresponding epoxides. Analysis of the influence of irradiation wavelength and intensity on the epoxidation suggests that light-excited electrons of CuNPs drive the reaction. The adatoms formed react with alkenes, producing the final product epoxides. We also observed interesting product stereoselectivity, predominantly generating the trans isomers for the epoxidation of stilbene (up to 97%). The findings reported here not only provide an effective and selective reaction system for alkene epoxidations but also are a step toward demonstrating the practical use of CuNPs as photocatalysts for various applications.
- Huang, Yiming,Liu, Zhe,Gao, Guoping,Xiao, Gang,Du, Aijun,Bottle, Steven,Sarina, Sarina,Zhu, Huaiyong
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p. 4975 - 4985
(2017/08/17)
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- Synthesis, characterization, density functional theory studies and antibacterial activity of a new Schiff base dioxomolybdenum(VI) complex with tryptophan as epoxidation catalyst
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A cis-dioxomolybdenum(VI) complex was prepared with MoO2(acac)2 and a Schiff base ligand (2-((2-hydroxybenzylidene)amino)-3-(1H-indol-3-yl)propanoic acid) derived from salicylaldehyde and l-tryptophan in ethanol and designated as [MoO2(Sal-Tryp)(EtOH)]. It was characterized using several techniques including thermogravimetric and elemental analyses and mass, Fourier transform infrared and UV–visible spectroscopies. Theoretical calculations were performed using density functional theory for studying the molecular structure. An in vitro antibacterial activity evaluation showed that [MoO2(Sal-Tryp)EtOH] complex exhibits good inhibitory effects against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria in comparison to standard antibacterial drugs. It was also found that [MoO2(Sal-Tryp)EtOH] complex successfully catalyses the epoxidation of cyclooctene, norbornene, cyclohexene, styrene, α-methylstyrene and trans-stilbene, with 45–100% conversions and 64–100% selectivities. Based on the obtained results, the heterogeneity and reusability of the catalyst seem promising.
- Asgharpour, Zeinab,Farzaneh, Faezeh,Ghiasi, Mina,Azarkish, Mohammad
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- Metallophthalocyanine intercalated layered double hydroxides as an efficient catalyst for the selective epoxidation of olefin with oxygen
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Varied metallophthalocyanine intercalated layered double hydroxides (LDHs) as bifunctional hybrid catalysts for selective epoxidation have been prepared and characterized. Systematic characterizations suggested the successful intercalation of the metallophthalocyanines into the interlayer of ZnAl LDHs. The synthesized hybrid exhibited excellent catalytic activity in the selective epoxidation of various olefins through O2/isobutaldehyde system. The basicity of the hybrid benefits to the selectivity of epoxide, and the bifunctional roles of the catalyst in the reaction have been discussed and verified by a series of controlled experiments. On the basis of obtained results, a probable mechanism of the epoxidation by the hybrid has been proposed and detailedly investigated. Under the catalysis of metallophthalocyanines intercalated LDHs in the presence of O2/isobutaldehyde, the production of epoxide undergoes two reaction paths. And two types of intermediates, namely acylperoxy radical and peroxyacid, are formed in the reaction, and the former is predominant.
- Zhou, Weiyou,Zhou, Jiacheng,Chen, Yong,Cui, Aijun,Sun, Fu'an,He, Mingyang,Xu, Zhixiang,Chen, Qun
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p. 191 - 200
(2017/06/09)
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- Aerobic Stereoselective Oxidation of Olefins on a Visible-Light-Irradiated Titanium Dioxide-Cobalt-Ascorbic Acid Nanohybrid
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A visible-light-driven photocatalytically active nanocrystalline TiO2 was prepared by surface modification with a cobalt-ascorbic acid complex. The photocatalyst exhibited high activity and excellent chemo-, diastereo-, and stereoselectivities
- Jafarpour, Maasoumeh,Feizpour, Fahimeh,Rezaeifard, Abdolreza
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supporting information
p. 235 - 238
(2017/01/25)
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- Reductive activation of O2 by a bioinspired Fe complex for catalytic epoxidation reactions
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Aerobic epoxidation of olefins catalyzed by iron complexes without the use of a sacrificial coreductant is unknown. We report the reductive activation of O2 by a bioinspired [(bTAML)FeIII(H2O)]- (1) complex to catalyze the epoxidation of alkenes with TONs of up to 80. Spectroscopic and kinetic evidence indicates the involvement of FeV(O) as the active oxidant during the reaction.
- Singh, Kundan K.,Gupta, Sayam Sen
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supporting information
p. 5914 - 5917
(2017/07/11)
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- NiO promoted CuO-NiO/SBA-15 composites as highly active catalysts for epoxidation of olefins
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In this paper, CuO-NiO supported on mesoporous silica SBA-15 was developed using the ultrasonic post-grafting method. The bi-metallic oxides were well-dispersed in very small sizes in the mesoporous channels, and the presence of NiO enhanced the surface content of CuO, leading to a redistribution of CuO and good dispersion of CuO nanoparticles, which were characterized by high-resolution transmission electron microscopy (HRTEM), XRD and N2 adsorption and desorption isotherm examination. Compared with the CuO/SBA-15 or NiO/SBA-15, the electron transfer that occurred between the two metal oxides and high dispersion of the active components improved the overall selective olefin oxidation.
- Tang, Yinhai,Gao, Hongyi,Yang, Mu,Wang, Ge,Li, Jie,Zhang, Huan,Tao, Zhang
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p. 8543 - 8548
(2016/10/11)
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- Synthesis, characterization, DFT studies, and immobilization of cobalt(II) complex with N,N′,N″-tris(2-pyrimidinyl)dimethylentriamine on modified iron oxide as oxidation catalyst
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[Co3(PDMT)Cl6] complex, in which PDMT is N,N′,N″-tris(2-pyrimidinyl)dimethylentriamine was prepared in cyclohexanol under hydrothermal condition. At first, the crystal structure of PDMT was solved based on the Rietveld method by using laboratory X-ray powder diffraction data. The molecular geometry of the ligand and complex were optimized by B3LYP method. In order to heterogenize the prepared complex, it was immobilized on the modified Fe3O4 nanoparticles with (3-aminopropyl)trimethoxysilane (APTMS). The prepared compound designated as Fe3O4SiO2-2APTMS[Co3(PDMT)Cl6] was found to successfully catalyze the epoxidation of cyclooctene, styrene, cyclohexene, trans-stilbene as well as oxidation of fluorene, diphenylmethane, ethylbenzene, adamantane, cyclohexane, cyclooctane and norbornene with TBHP as oxidant with 25-100% conversions and 18-100% selectivities. Ligand, complex and Fe3O4SiO2-2APTMS[Co3(PDMT)Cl6] were characterized by FT-IR, TEM, XRD, Mass, UV-Vis, DSC-TGA, NMR, GC and GC-Mass techniques.
- Sharbatdaran, Masoomeh,Farzaneh, Faezeh,Larijani, Majid Mojtahedzadeh,Salimi, Alireza,Ghiasi, Mina,Ghandi, Mehdi
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p. 264 - 275
(2016/06/09)
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- Cis-Dihydroxylation of electron deficient olefins catalysed by an oxo-bridged diiron(III) complex with H2O2
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Room temperature oxidation of olefins catalysed by a symmetrical (μ-oxo)(μ-hydroxo)diiron(III) complex (1) based on the amino pyridyl ligand bpmen (bpmen = N,N′-dimethyl-N,N′-bis(2-pyridyl methyl)ethane-1,2-diamine) with hydrogen peroxide under the conditions of limiting substrate is described. Excellent substrate conversions have been achieved under ambient reaction conditions. The olefin oxidation efficacy of the 1/H2O2 system has been found to get improved in presence of acetic acid. The catalytic system has been shown to oxidise electron-deficient olefins to the corresponding cis-diols, while epoxidation is favoured in case of electron-rich olefins. The μ-oxo diiron(III) core of the catalyst 1 has been found be regenerated after the catalytic turnovers. Addition of a second batch of substrate and oxidant at the end of the olefin oxidation results in the formation of almost identical amounts of epoxides/diols. Moreover, the regenerated catalyst exhibits a significantly higher preference towards the oxidation of electron-deficient olefins.
- Kejriwal, Ambica,Biswas, Sachidulal,Biswas, Achintesh N.,Bandyopadhyay, Pinaki
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- Superparamagnetic Core–Shell Metal–Organic Framework Fe3O4/Cu3(btc)2 Microspheres and Their Catalytic Activity in the Aerobic Oxidation of Alcohols and Olefins
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Core–shell structured Fe3O4/Cu3(btc)2 (btc = 1,3,5-benzenetricarboxylate) microspheres have been successfully synthesized by coating the metal–organic frameworks on poly(acrylic acid) (PAA) functionalized Fe3O4 microspheres by the layer-by-layer assembly method. The MOF composite exhibited excellent catalytic activity in the aerobic oxidation of alcohols and the epoxidation of olefins due to the porosity of MOFs and large amount of readily accessible Cu2+. Furthermore, the catalyst could be easily segregated from the catalytic system by using an external magnetic field due to its magnetic properties. The heterogeneous catalyst displayed good reusability and broad reagent scope in the aerobic oxidation of alcohols and epoxidation of olefins.
- Li, Jie,Gao, Hongyi,Tan, Li,Luan, Yi,Yang, Mu
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p. 4906 - 4912
(2016/10/26)
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- A synergistic effect of a cobalt Schiff base complex and TiO2 nanoparticles on aerobic olefin epoxidation
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In this study, a cobalt Schiff base complex and TiO2 nanoparticles exhibited a synergistic effect on the visible-light photocatalytic activity in the aerobic oxidation of various olefins in the absence of a reducing agent. The catalyst structure was found to be well preserved after the oxidation reaction and the catalyst could be reused at least five times.
- Jafarpour, Maasoumeh,Kargar, Hossein,Rezaeifard, Abdolreza
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p. 79085 - 79089
(2016/09/09)
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- Manganese(III) Tetraphenylporphyrin Encapsulated by Ion-Modified Hexagonal Mesoporous Silica With Unexpected Enhanced Epoxidation Selectivity
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Tetraphenylporphyrin manganese (III) chloride (Mn-TPP) was encapsulated into hexagonal mesoporous silica (HMS) modified by different Lewis acid ions Al, Ti, Zr, and W, which have been tested for selective oxidation of unsaturated olefins and more challeng
- Zhang, Weijie,Jiang, Pingping,Wang, Ying,Zhang, Jian,Zhang, Pingbo
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p. 1765 - 1772
(2016/08/05)
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- A new Organopalladium compound containing four Iron (III) Porphyrins for the selective oxidation of alkanes/alkenes by t-BuOOH
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Two iron(III) tetraphenyl porphyrin catalytic units are connected by an azo-link to form the dimeric compound A. The compound A was then reacted with Pd 2+ to make a tetrameric iron(III) porphyrin complex B with all four iron(III) catalytic sites open to the substrates and reactants. Both the compounds were characterized spectroscopically and the results of homogeneous oxidation of some alkanes and alkenes with t-BuOOH in presence of catalytic quantities of A and B have indicated remarkable improvement in selectivity and efficiency of A over the monomeric catalyst and B over A. [Figure not available: see fulltext.]
- Singh, Manoj Kumar,Bandyopadhyay, Debkumar
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p. 383 - 389
(2016/03/16)
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- Fighting Fenton Chemistry: A Highly Active Iron(III) Tetracarbene Complex in Epoxidation Catalysis
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Organometallic Fe complexes with exceptionally high activities in homogeneous epoxidation catalysis are reported. The compounds display FeII and FeIII oxidation states and bear a tetracarbene ligand. The more active catalyst exhibits activities up to 183 000 turnovers per hour at room temperature and turnover numbers of up to 4300 at -30°C. For the FeIII complex, a decreased Fenton-type reactivity is observed compared with FeII catalysts reported previously as indicated by a substantially lower H2O2 decomposition and higher (initial) turnover frequencies. The dependence of the catalyst performance on the catalyst loading, substrate, water addition, and the oxidant is investigated. Under all applied conditions, the advantageous nature of the use of the FeIII complex is evident.
- Kück, Jens W.,Anneser, Markus R.,Hofmann, Benjamin,P?thig, Alexander,Cokoja, Mirza,Kühn, Fritz E.
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p. 4056 - 4063
(2015/12/17)
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- Prussian blue analogues as heterogeneous catalysts for epoxidation of styrene
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The catalytic epoxidation of styrene was carried out using tert-butyl hydroperoxide (TBHP) in the presence of Prussian blue analogues (PBA) as catalysts and the reaction parameters of the epoxidation, such as temperature, solvent and reaction time, have been optimized. Optimum reaction conditions led to 96% conversion of styrene with selectivity in styrene epoxide equal to 64%. Furthermore, a kinetic investigation of the epoxidation of styrene with TBHP has been studied, a first order with respect to the concentrations of styrene, TBHP and catalyst were determined and an apparent activation energy value of 100.4 kJ mol-1 was obtained. This journal is
- Liang, Yanling,Yi, Chaoyong,Tricard, Simon,Fang, Jian,Zhao, Jihua,Shen, Weiguo
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p. 17993 - 17999
(2015/05/27)
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- Preparation of SnO2/graphene nanocomposite and its application to the catalytic epoxidation of alkenes with H2O2
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The in situ growth of SnO2 nanoparticles on graphene have been achieved via a hydrothermal method and the nanocomposites were used as an efficient catalyst for the epoxidation of alkenes with aqueous hydrogen peroxide in nitrile based systems for the first time. Furthermore, the SnO2/graphene nanocomposites could be readily recovered and reused for at least ten consecutive cycles without significant loss of activity and selectivity.
- Liu, Min,Wang, Xiaozhong,Chen, Yingqi,Dai, Liyan
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p. 61481 - 61485
(2015/08/03)
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- Synthesis, characterization and catalytic activities towards epoxidation of olefins of dinuclear copper(II) complexes
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Two copper(II) complexes, [Cu2(L1)Cl3].2H2O (1) and [Cu2(L2)(N3)Cl2] (2) where HL1 = 4-methyl-2,6-bis((2-morpholinoethylimino)methyl)phenol and HL2 = 4-methyl-2,6-bis((3-morpholinopropylimino)methyl)phenol have been synthesized and characterized by elemental analysis, various spectroscopic methods, TGA and single crystal X-ray diffraction analysis. Single crystal X-ray diffraction analysis reveals that in both the complexes, two copper atoms are linked by phenoxo oxygen atom and a bridging ligand, namely chloride and azide, respectively. These complexes have been used as catalyst for the epoxidation of cyclohexene, styrene, α-methyl styrene, trans-stilbene and norbornene using tert-butyl hydroperoxide as the oxidant in acetonitrile under mild conditions. All of the substrates undergo conversion to produce respective epoxide as the major product.
- Halder, Shibashis,Mukherjee, Aparajita,Ghosh, Koushik,Dey, Sudipto,Nandi, Mahasweta,Roy, Partha
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- Mononuclear Nonheme Iron(III)-Iodosylarene and High-Valent Iron-Oxo Complexes in Olefin Epoxidation Reactions
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High-spin iron(III)-iodosylarene complexes are highly reactive in the epoxidation of olefins, in which epoxides are formed as the major products with high stereospecificity and enantioselectivity. The reactivity of the iron(III)-iodosylarene intermediates is much greater than that of the corresponding iron(IV)-oxo complex in these reactions. The iron(III)-iodosylarene species - not high-valent iron(IV)-oxo and iron(V)-oxo species - are also shown to be the active oxidants in catalytic olefin epoxidation reactions. The present results are discussed in light of the long-standing controversy on the one oxidant versus multiple oxidants hypothesis in oxidation reactions. On active duty: High-spin iron(III)-iodosylarene complexes epoxidize olefins with high stereospecificity and enantioselectivity. The iron(III)-iodosylarene species, not high-valent iron(IV)- and iron(V)-oxo species, are the active oxidants in catalytic olefin epoxidation reactions. The present results resolve the long-standing controversy on the one oxidant versus multiple oxidants hypothesis in oxidation reactions.
- Wang, Bin,Lee, Yong-Min,Seo, Mi Sook,Nam, Wonwoo
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supporting information
p. 11740 - 11744
(2015/10/05)
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- Dioxomolybdenum(VI) complex immobilized on ascorbic acid coated TiO2 nanoparticles catalyzed heterogeneous oxidation of olefins and sulfides
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Addition of MoO2 (acac)2 to TiO2 coated with ascorbic acid (AA) under ultrasonic agitation resulted in a nanohybrid (TiO2/AA/MoO2) with size ranging between 20-25 nm. The structural and morphological characterization of the as-prepared nanohybrid was carried out by different techniques such as XRD, FT-IR, TGA and transmission electron microscopy (TEM). The catalytic performance of the TiO2/AA/MoO2 nanocomplex in the heterogeneous oxidation of olefins and sulfides using H2O2 in ethanol as a safe solvent was exploited. Our results clearly demonstrated the efficiency, selectivity and oxidative stability of the heterogeneous nanocatalyst providing its effective reusability and removing by-products. The catalytic activity of the TiO2/AA/MoO2 nanocomplex was strikingly different from other nanometer sized metal oxides such as m-ZrO2, MoO3, Fe3O4 and TiO2, as well as their nanocomposites such as TiO2/AA, ZrO2/AA/MoO2, MoO3/AA/MoO2 and Fe3O4/AA/MoO2.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Ghahramaninezhad, Mahboube,Feizpour, Fahimeh
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p. 442 - 452
(2018/04/16)
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- Non-redox metal ion promoted oxygen transfer by a non-heme manganese catalyst
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This work demonstrates that non-redox metal ions as Lewis acids can sharply improve the oxygen transfer efficiency of a manganese(II) catalyst having a non-heme ligand. In the absence of Lewis acid, oxidation of a manganese(II) complex will generate the k
- Chen, Zhuqi,Yang, Ling,Choe, Cholho,Lv, Zhanao,Yin, Guochuan
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supporting information
p. 1874 - 1877
(2015/02/05)
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- Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer
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Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(ii) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(ii) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al3+ to the manganese(ii) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(ii) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, MnIII-(μ-O)2-MnIV. The presence of a Lewis acid like Al3+ causes the dissociation of this diamond MnIII-(μ-O)2-MnIV core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.
- Choe, Cholho,Yang, Ling,Lv, Zhanao,Mo, Wanling,Chen, Zhuqi,Li, Guangxin,Yin, Guochuan
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p. 9182 - 9192
(2015/05/20)
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- Immobilized V-MIL-101 on modified Fe3O4 nanoparticles as heterogeneous catalyst for epoxidation of allyl alcohols and alkenes
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As a new heterogeneous catalyst, Fe3O4 nanoparticles were prepared and modified with sodium silicate and (3-aminopropyl) trimethoxysilane (APTMS) followed by complexation with V-MIL-101 and designated as Fe3O4@SiO2@APTMS@VMIL-101. It was characterized using FTIR, TEM, and VSM techniques. The Fe3O4@SiO2@APTMS@VMIL-101 was found to successfully catalyze the epoxidation of allyl alcohols and alkenes with tert-butylhydroperoxide (TBHP) in moderate to high yields. The epoxidation of trans-stilbene, norbornen, cyclooctene, geraniol, trans-2-hexene-1ol and 1-octene-3-ol with 100% selectivity is promising. Investigation of the stability and reusability of Fe3O4@SiO2@APTMS@V-MIL-101 revealed the heterogeneity character of the catalyst with no desorption during the course of epoxidation reactions. High yields, clean reactions, ease of catalyst separation and recyclability of the solid catalyst are some advantages of this method.
- Farzaneh, Faezeh,Sadeghi, Yasaman
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p. 275 - 281
(2015/03/03)
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- Nanoscaled copper metal-organic framework (MOF) based on carboxylate ligands as an efficient heterogeneous catalyst for aerobic epoxidation of olefins and oxidation of benzylic and allylic alcohols
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Aerobic epoxidation of olefins at a mild reaction temperature has been carried out by using nanomorphology of [Cu3(BTC)2 ] (BTC = 1,3,5-benzenetricarboxylate) as a high-performance catalyst through a simple synthetic strategy. An aromatic carboxylate ligand was employed to furnish a heterogeneous copper catalyst and also serves as the ligand for enhanced catalytic activities in the catalytic reaction. The utilization of a copper metal-organic framework catalyst was further extended to the aerobic oxidation of aromatic alcohols. The shape and size selectivity of the catalyst in olefin epoxidation and alcohol oxidation was investigated. Furthermore, the as-synthesized copper catalyst can be easily recovered and reused several times without leaching of active species or significant loss of activity.
- Qi, Yue,Luan, Yi,Yu, Jie,Peng, Xiong,Wang, Ge
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p. 1589 - 1597
(2015/01/30)
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- Visible light induced oxygenation of alkenes with water sensitized by silicon-porphyrins with the second most earth-abundant element
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Silicon as the second most abundant element on Earth was effectively utilized as the central atom in the porphyrin to induce photochemical oxygenation of alkenes as the first example of photocatalytic reaction through activation of water molecule in the presence of K2PtCl6 as an electron acceptor. Oxygen atom of water was confirmed to be incorporated in the oxygenated product by the photoreaction with H218O. The excited triplet state of silicon porphyrin was revealed to be responsible for the photochemical oxygenation. The one-electron oxidized silicon porphyrin was predicted by DFT calculation to have its spin population mostly on the axially ligated hydroxyl oxygen atom. The oxyl radical character of the axial ligand could rationalize the oxygenation reaction.
- Remello, Sebastian Nybin,Hirano, Takehiro,Kuttassery, Fazalurahman,Nabetani, Yu,Yamamoto, Daisuke,Onuki, Satomi,Tachibana, Hiroshi,Inoue, Haruo
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p. 176 - 183
(2015/10/28)
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- Synthesis and catalytic properties of titanium containing extra-large pore zeolite CIT-5
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Titanium containing extra-large pore zeolite CIT-5 (IZA code: CFI) was successfully prepared by direct synthesis using Cab-O-Sil M5 and titanium(IV) butoxide in the presence of LiOH. N-Methylsparteinium hydroxide was used as a structure directing agent. The product crystallized into thin plate crystals with an approximate size of 20 × 5 × 0.2 μm. The lowest achieved Si/Ti ratio was 23. The necessary duration of hydrothermal synthesis increased with increasing concentration of Ti in the reaction mixture from 11 days (Si/Ti = 63 in product) to 17 days (Si/Ti = 36) at 155 C. Prepared Ti-CFI samples exhibit BET surface areas in the range of 308-346 m2/g and micropore volumes of 0.094-0.097 cm3/g. CFI possesses extra-large pores (14-ring, 7.2 × 7.5 A?) accessible for bulky molecules, therefore, Ti-CFI is a useful catalyst for epoxidation of double bonds in bulky molecules used in perfumery and pharmacy. The Ti-CFI samples proved to be catalytically active in epoxidation of 1-octene, cyclooctene, α-pinene, and norbornene with hydrogen peroxide as oxidation agent.
- P?ech, Jan,Kub?, Martin,?ejka, Ji?í
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- A new halide-free efficient reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH 3)2N]3[SiO4H(WO5) 3] for olefin epoxidation, oxidation of sulfides and alcohols with hydrogen peroxide
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A new reaction-controlled phase-transfer catalyst based on silicotungstate of [(C18H37)2(CH3) 2N]3[SiO4H(WO5)3] for oxidation of hydrocarbons is developed. The catalyst is a new heteropoly compound with silicon as heteroatom, which is different to the previously reported reaction-controlled phase transfer catalysts that were composed of quaternary ammonium heteropolyoxotungstates of [π-C5H 5N(CH2)15CH3]3[PW 4O16] and [π-C5H5N(CH 2)15CH3]3[PW4O 32] with phosphorus as heteroatom. The oxidation of various alkenes (such as linear terminal olefins, internal olefins, cyclic olefins and unactivated alkenes) to epoxides, sulfides to sulfoxides and sulfones, alcohols to carbonyl compounds, are successfully catalyzed by this recyclable and environmentally benign catalyst using H2O2 as oxidant and ethyl acetate as solvent. This catalyst is not only capable of catalyzing homogeneous oxidation of organic substrates with unique reaction-controlled phase-transfer character, but also avoids the use of toxic solvents. The catalyst could be easily recovered and reused after reaction, and the epoxidation of cyclohexene was performed twenty times without obvious loss in activity. The fresh catalyst and the used one were characterized by ICP, IR, UV-vis, 29Si MAS NMR and 183W NMR in detail. the Partner Organisations 2014.
- Ma, Baochun,Zhao, Wei,Zhang, Fuming,Zhang, Yingshuai,Wu, Songyun,Ding, Yong
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p. 32054 - 32062
(2014/08/18)
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- Catalytic activity and selectivity of reusable α-MoO3 nanobelts toward oxidation of olefins and sulfides using economical peroxides
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The novel catalytic activity of α-MoO3 nanobelts prepared by a new and safe sol-gel method for the epoxidation of olefins and oxidation of sulfides to sulfoxides using H2O2 in ethanol as a safe solvent has been exploited. The reactions also proceeded efficiently in the presence of tert-butyl hydroperoxide (TBHP). Good/high yields and excellent selectivity resulted. The ammonia TPD profile demonstrated strong acidic sites in synthesized α-MoO3 nanobelts, which generated different catalytic activity than the bulk material. The separation and reuse of this heterogeneous nanocatalyst was simple, effective and economical in the presented oxidation methods.
- Jafarpour, Maasoumeh,Ghahramaninezhad, Mahboube,Rezaeifard, Abdolreza
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p. 1601 - 1608
(2014/01/06)
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- Synthesis, characterization and catalytic activity of oleic acid-coated TiO2 nanoparticles carrying MoO2 (acac)2 in the oxidation of olefins and sulfides using economical peroxides
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Titanium oxide nanoparticles were synthesized by a modified polymerized complex derived sol-gel method followed by coating with oleic acid (OA) to modify their surface. The reaction with MoO2 (acac)2 yielded the TiO2-OA-MoO2 nanocomposite as a supported cis-dioxomolybdenum complex. The structural and morphological characterization of the as-prepared TiO2 and TiO2-OA-MoO2 were carried out by different techniques such as XRD, FT-IR, TGA and TEM. The catalytic activity of the TiO2-OA-MoO2 nanocomplex in the epoxidation of olefins and oxidation of sulfides to sulfoxides using H 2O2 in ethanol as a safe solvent was investigated. The reactions also proceeded efficiently in the presence of tert-butylhydroperoxide (TBHP). Good/high yields and excellent selectivity were obtained. The recovery of the title heterogeneous nanocatalyst was easy and efficient and its catalytic activity was strikingly different from other nanooxometals such as m-ZrO 2, MoO3, Fe3O4 and TiO2, as well as their nanocomposites such as TiO2-OA, ZrO 2-OA-MoO2, MoO3-OA-MoO2 and Fe 3O4-OA-MoO2. the Partner Organisations 2014.
- Jafarpour, Maasoumeh,Ghahramaninezhad, Mahboube,Rezaeifard, Abdolreza
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p. 2917 - 2926
(2014/07/07)
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- Silica-coated magnetite nanoparticles stabilized simple Mn-tetraphenylporphyrin for aqueous phase catalytic oxidations with tert-butyl hydroperoxide
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An economic and environmentally friendly system for efficient and selective oxidation of industrially and biologically important substrates in water using tert-butyl hydroperoxide catalyzed by a new magnetically recoverable Mn-porphyrin was developed. The easily prepared heterogeneous catalyst was characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, FT-IR and UV-vis spectroscopy. The size of the catalyst was estimated to be about 10 nm. The thermal gravimetric analysis demonstrated that the nanocatalyst was thermally stable up to almost 300 °C. The reactivity, selectivity and scope of the reaction were investigated with a variety of olefins, saturated hydrocarbons, alcohols and organosulfur compounds. The reactions proceeded smoothly in the absence of surfactants, organic co-solvents and thus take place "on water". The separation and recycling of nanocatalyst as well as isolation of water-insoluble products were simple, effective and economical in this clean oxidation method.
- Rezaeifard, Abdolreza,Farshid, Parisa,Jafarpour, Maasoumeh,Moghaddam, Gholamreza Kardan
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p. 9189 - 9196
(2014/03/21)
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- The catalytic efficiency of Fe-porphyrins supported on multi-walled carbon nanotubes in the heterogeneous oxidation of hydrocarbons and sulfides in water
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Novel recoverable biomimetic catalysts were prepared by the coordinative anchoring of an iron(iii) meso-tetraphenyl porphyrin complex [Fe(TPP)Cl] and some derivatives on the activated multi-walled carbon nanotube (AMWCNT) via hydroxyl functionality (Fe-Por-AMWCNT). The simple heterogeneous catalyst [Fe(TPP)Cl-MWCNT] was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman, FT-IR and UV-vis spectroscopy. The amount of catalyst loading on the nanotubes, was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The thermogravimetric analysis (TGA) demonstrated that the nanocatalyst was thermally stable up to almost 400 °C, exhibiting high thermostability. The epoxidation of olefins and the oxidation of saturated hydrocarbons to the related ketones and also sulfides to the sulfones by aqueous solution of tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO 5, TBAOX) were efficiently enhanced with excellent selectivity under the influence of the separable nanocatalyst with very low catalyst loading. Sulfoxides could also be selectively produced in ethanol, which makes the title methodology a good alternative for both sulfoxide and sulfone production. The separation and recycling of the catalyst and oxidant by-products were simple, effective and economical in this clean oxidation method. The FT-IR, UV-vis and leaching experiments after ten successive cycles showed that the catalyst was most strongly anchored to the MWCNT support. The Royal Society of Chemistry 2014.
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh
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p. 1960 - 1969
(2014/06/24)
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- Epoxidation of alkenes using inorganic polymer of silica zirconia molybdate as catalyst
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Silica zirconia sulfate was prepared by sol-gel copolymerization of the sulfated zirconium octanoxide and tetraethylorthosilicate (TEOS). Active polymer oxidation catalysts were obtained by introducing sodium molybdate into the polymer by a ligand exchange reaction. The prepared inorganic polymer designated as SZ-Mo was characterized by FT-IR, SEM, XRD, N2 sorption isotherms, and ICP techniques. It was found that SZ-Mo successfully catalyzes the epoxidation of cyclooctene, cyclohexene, trans-stilbene, and norbornene with 22-95% conversion and 60-100% selectivity. The dependence of the SZ-Mo catalytic activity to the amount of adsorbed Mo within the polymer as well as the study of catalyst stability during the course of reactions will be described in this presentation.
- Sharbatdaran,Farzaneh,Larijani
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- Combined experimental and theoretical study on the reactivity of Compounds I and II in horseradish peroxidase biomimetics
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For the exploration of the intrinsic reactivity of two key active species in the catalytic cycle of horseradish peroxidase (HRP), Compound I (HRP-I) and Compound II (HRP-II), we generated in situ [FeIV=O(TMP+?)(2-MeIm)] + and [FeIV=O(TMP)(2-MeIm)]0 (TMP = 5,10,15,20-tetramesitylporphyrin; 2-MeIm = 2-methylimidazole) as biomimetics for HRP-I and HRP-II, respectively. Their catalytic activities in epoxidation, hydrogen abstraction, and heteroatom oxidation reactions were studied in acetonitrile at -15 °C by utilizing rapid-scan UV/Vis spectroscopy. Comparison of the secondorder rate constants measured for the direct reactions of the HRP-I and HRP-II mimics with the selected substrates clearly confirmed the outstanding oxidizing capability of the HRP-I mimic, which is significantly higher than that of HRP-II. The experimental study was supported by computational modeling (DFT calculations) of the oxidation mechanism of the selected substrates with the involvement of quartet and doublet HRP-I mimics (2,4Cpd I) and the closed-shell triplet spin HRP-II model (3Cpd II) as oxidizing species. The significantly lower activation barriers calculated for the oxidation systems involving 2,4Cpd I than those found for 3Cpd II are in line with the much higher oxidizing efficiency of the HRP-I mimic proven in the experimental part of the study. In addition, the DFT calculations show that all three reaction types catalyzed by HRP-I occur on the doublet spin surface in an effectively concerted manner, whereas these reactions may proceed in a stepwise mechanism with the HRP-II mimic as oxidant. However, the high desaturation or oxygen rebound barriers during C-H bond activation processes by the HRP-II mimic predict a sufficient lifetime for the substrate radical formed through hydrogen abstraction. Thus, the theoretical calculations suggest that the dissociation of the substrate radical may be a more favorable pathway than desaturation or oxygen rebound processes. Importantly, depending on the electronic nature of the oxidizing species, that is, 2,4Cpd I or 3Cpd II, an interesting region-selective conversion phenomenon between sulfoxidation and H-atom abstraction was revealed in the course of the oxidation reaction of dimethylsulfide. The combined experimental and theoretical study on the elucidation of the intrinsic reactivity patterns of the HRP-I and HRP-II mimics provides a valuable tool for evaluating the particular role of the HRP active species in biological systems.
- Ji, Li,Franke, Alicja,Brindell, Malgorzata,Oszajca, Maria,Zahl, Achim,Van Eldik, Rudi
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p. 14437 - 14450
(2015/04/14)
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- Hierarchical PS/PANI nanostructure supported Cu(ii) complexes: Facile synthesis and study of catalytic applications in aerobic oxidation
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Hierarchical heterogeneous copper catalysts were prepared by immobilization of a homogeneous copper(ii) complex on the surface of polystyrene/polyaniline (PS/PANI) microspheres with oriented PANI nanofibers. EDX element maps and XPS spectra indicated that Cu2+ ions strongly coordinated with PANI imine. PS/PANI@Cu(OSO2CF3)2 exhibited excellent catalytic activity for selective aerobic oxidation of alcohols and highly efficient aerobic epoxidation of alkenes under mild conditions. The supported copper(ii) catalyst maintained high levels of conversion and selectivity in these reactions after six cycles and showed good stability. This journal is
- Yu, Jie,Luan, Yi,Qi, Yue,Hou, Junying,Dong, Wenjun,Yang, Mu,Wang, Ge
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p. 55028 - 55035
(2015/02/19)
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- Nanoaggregates of simple Mn porphyrin complexes as catalysts for the selective oxidation of hydrocarbons
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A stable suspension of simple manganese(III) meso-tetraphenylporphyrin nanoaggregates was prepared by a host-guest procedure, in which ethanol and water are used as "green" solvents. The organic nanoparticles were studied by dynamic light scattering (DLS), AFM, and UV/Vis and fluorescence spectroscopy. The results indicate that the nanoaggregates have a spherical morphology with sizes between 15-40 nm. The epoxidation of olefins and oxygenation of saturated hydrocarbons by PhI(OAc)2 were efficiently enhanced with excellent selectivity under the influence of simple Mn(TPP)OAc (TPP = meso-tetraphenylporphyrin) nanoparticles. Enhanced stabilities and activities were achieved with nanostructured Mn catalysts compared to those of the individual counterparts in solution according to turnover numbers and UV/Vis studies. The title nanocatalyst facilitates a greener reaction because the reaction solvent is a water/ethanol mixture and PhI(OAc)2 is safe to use. The efficiency of the oxidation system depends critically upon the steric hindrances and electronic structures of both nitrogen donor ligands and porphyrin nanoparticles. Copyright
- Rezaeifard, Abdolreza,Soltani, Vahideh,Jafarpour, Maasoumeh
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p. 2657 - 2664
(2013/06/05)
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