- Aminopropyl group-modified SBA-15 covalent attachment Mn(salen) complexes as catalysts for styrene epoxidation
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A series of aminopropyl group-modified ordered mesoporous silica materials impregnated with Mn(salen) were prepared using successive grafting procedures. The prepared composite catalysts were well characterized by inductively coupled plasma atomic emissio
- Liu, Lili,Hu, Jianglei,He, Jiaojiao,Lu, Haojie,Xu, Yong,Shi, Fengwei
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- Epoxidation of styrene to styrene oxide: Synergism of heteropoly acid and phase-transfer catalyst under Ishii-Venturello mechanism
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Epoxidation of olefinic double bonds is of considerable importance in a variety of industries. Epoxides are raw materials for a wide variety of chemicals such as glycols, alcohols, carbonyl compounds, alkanolamines, and polymers such as polyesters, polyur
- Yadav,Pujari
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- Are MnIV species involved in Mn(salen)-satalyzed Jacobsen-Katsuki epoxidations? A mechanistic elucidation of their formation and reaction modes by EPR spectroscopy, mass-spectral analysis, and product studies: Chlorination versus oxygen transfer
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EPR and ESI-MS/MS evidence is presented that in the absence of an olefinic substrate the reaction between the MnIII(salen) complexes A1 (X = Cl) and A2 (X = PF6) and PhIO or NaOCl as oxygen sources leads to paramagnetic MnIV(salen) complexes. Depending on the solvent and the counterion, two distinct MnIV-(salen) complexes intervene. In CH2Cl2, regardless of the counterion, a ClOMnIV(salen) complex (B1) and a HOMnIV(salen) complex (B1′) are formed by Cl and H atom abstraction from CH2Cl2, and the latter deprotonates to the neutral OMnIV(salen) complex (B2). In EtOAc as solvent, only the complex B2 is obtained from A1 (X = Cl), presumably by inner-sphere electron transfer from the chloride ion. The MnIV(salen) complexes display the following reaction modes toward 1,2-dihydronaphthalene (1), styrene (2), and the radical probe 3 as substrates: Complex B1 chlorinates the olefins 1/2 through an electrophilic pathway to yield the 1,2-dichloro adducts 1a/2a and the chlorohydrins 1b/2b (nucleophilic trapping of the initially formed benzylic cation), while with olefin 3 the ring-opened dichloro product 3a results. Complex B2, however, epoxidizes these olefins through a radical pathway, as evidenced by the formation of isomerized stilbene oxide 4c (cis/trans ratio 36: 64) from cis-stilbene (4). The relevance of these paramagnetic MnIV(salen) species in Jacobsen-Katsuki catalytic epoxidations is scrutinized.
- Adam, Waldemar,Mock-Knoblauch, Cordula,Saha-Moeller, Chantu R.,Herderich
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- Barium hexaferrite (BaFe12O19) nanoparticles as highly active and magnetically recoverable catalyst for selective epoxidation of styrene to styrene oxide
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Herein, we are reporting the use of pure single phase barium hexaferrite (BaFe12O19) nanoparticles as an efficient catalyst for epoxidation of styrene. BaFe12O19 nanocatalysts exhibit high conversion of styrene
- Chandel, Madhurya,Ghosh, Barun Kumar,Moitra, Debabrata,Ghosh, Narendra Nath
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- Gold nanoparticles supported on cellulose aerogel as a new efficient catalyst for epoxidation of styrene
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A new efficient heterogeneous catalyst was introduced for the epoxidation of styrene. The catalyst was obtained from deposition of gold nanoparticles on the cellulose aerogel. The catalyst was characterized with XRD, TGA, EDX, BET, FAAS and SEM. High yield and excellent selectivity were achieved for the epoxidation of styrene in solvent-free conditions at room temperature using H2O2 as a green oxidant during 1?h. The reaction has some advantages such as solvent-free and mild reaction conditions, low catalyst loading, high yield, excellent selectivity, green oxidant and short reaction duration. In addition, the catalyst is recyclable and applicable for six times without decrease in yield.
- Keshipour, Sajjad,Khezerloo, Masoumeh
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- Manganese triacetate as an efficient catalyst for bisperoxidation of styrenes
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A method was developed for the bisperoxidation of styrenes with tert-butyl hydroperoxide in the presence of a catalytic amount of manganese(III) acetate. It was shown that compounds of manganese in oxidation states 2, 4, and 7 also catalyze this reaction. The target [1,2-bis(tert-butylperoxy)ethyl]arenes were synthesized in yields from 46 to 75%.
- Terent'ev, Alexander O.,Sharipov, Mikhail Yu.,Krylov, Igor B.,Gaidarenko, Darya V.,Nikishin, Gennady I.
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- Colloidal gold immobilized on mesoporous silica as a highly active and selective catalyst for styrene epoxidation with H2O2
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Colloidal gold nanoparticles were synthesized by different procedures affording suspensions with two different mean sizes (2 and 5 nm). Au catalysts were prepared by sol immobilization onto several silica frameworks with different 2D and 3D mesoporosities. The catalysts were tested in styrene oxidation reactions showing excellent efficiency and selectivity. The effect of nanoparticle size and mesoporous framework on the physical and catalytic properties of the final materials was studied. The most selective catalyst was prepared from the 5 nm Au nanoparticles and the more interconnected silica framework (3D mesoporosity).
- Linares,Canlas,Garcia-Martinez,Pinnavaia
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- Self-assembly of reverse micelle nanoreactors by zwitterionic polyoxometalate-based surfactants for high selective production of β?hydroxyl peroxides
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Surfactants with polyoxometalates (POMs) as polar head groups have shown fascinating self-assembly behaviors and various functional applications. However, self-assembly them into reverse micelles is still challenging owing to the large molecular size and intermolecular strong electrostatic repulsions of POM heads. In this work, a zwitterionic POM-based surfactant was synthesized by covalently grafting two cationic long alkyl tails onto the lacunary site of [PW11O39]7?. With decreased electrostatic repulsions and increased hydrophobic effect, the POM-based reverse micelles with an average diameter of 5 nm were obtained. Interestingly, when these reverse micelles were applied for catalyzing the oxidation of styrene, an unprecedented β?hydroxyl peroxide compound of 2?hydroxyl-2-phenylethan-1?tert-butylperoxide was produced in high selectivity of 95.2%. In comparison, the cetyltrimethylammonium electrostatically encapsulated POMs mainly generated the epoxides or 1,2-diols. A free radical mechanism was proposed for the oxidation reaction catalyzed by the zwitterionic POM surfactants.
- An, Sai,Chang, Wen,Hu, Guicong,Qi, Bo,Song, Yu-Fei
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supporting information
(2022/03/08)
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- Catalytic oxygen atom transfer promoted by tethered Mo(VI) dioxido complexes onto silica-coated magnetic nanoparticles
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The preparation of three novel active and stable magnetic nanocatalysts for the selective liquid-phase oxidation of several olefins, has been reported. The heterogeneous systems are based on the coordination of cis-MoO2 moiety onto three different SCMNP@Si-(L1-L3) magnetically active supports, functionalized with silylated acylpyrazolonate ligands L1, L2 and L3. Nanocatalysts thoroughly characterized by ATR-IR spectroscopy, TGA and ICP-MS analyses, showed excellent catalytic performances in the oxidation of conjugated or unconjugated olefins either in organic or in aqueous solvents. The good magnetic properties of these catalytic systems allow their easy recyclability, from the reaction mixture, and reuse over five runs without significant decrease in the activity, either in organic or water solvent, demonstrating their versatility and robustness.
- Colaiezzi, Roberta,Crucianelli, Marcello,Di Giuseppe, Andrea,Ferella, Francesco,Lazzarini, Andrea,Paolucci, Valentina
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- Efficient and selective oxidation of hydrocarbons with tert-butyl hydroperoxide catalyzed by oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles
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The catalytic activity of an oxidovanadium(IV) unsymmetrical Schiff base complex supported on γ-Fe2O3 magnetic nanoparticles, γ-Fe2O3@[VO(salenac-OH)] in which salenac-OH = [9-(2′,4′-dihydroxyphenyl)-5,8-diaza-4
- Ardakani, Mehdi Hatefi,Sabet, Mohammad,Samani, Mahnaz
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- Oxygen Atom Transfer Mechanism for Vanadium-Oxo Porphyrin Complexes Mediated Aerobic Olefin Epoxidation
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The development of catalytic aerobic epoxidation by numerous metal complexes in the presence of aldehyde as a sacrificial reductant (Mukaiyama epoxidation) has been reported, however, comprehensive examination of oxygen atom transfer mechanism involving free radical and highly reactive intermediates has yet to be presented. Herein, meso-tetrakis(pentafluorophenyl) porphyrinatooxidovanadium(IV) (VOTPFPP) was prepared and proved to be efficient toward aerobic olefin epoxidation in the presence of isobutyraldehyde. In situ electron paramagnetic resonance spectroscopy (in situ EPR) showed the generation, transfer pathways and ascription of free radicals in the epoxidation. According to the spectral and computational studies, the side-on vanadium-peroxo complexes are considered as the active intermediate species in the reaction process. In the cyclohexene epoxidation catalyzed by VOTPFPP, the kinetic isotope effect value of 1.0 was obtained, indicating that epoxidation occurred via oxygen atom transfer mechanism. The mechanism was further elucidated using isotopically labeled dioxygen experiments and density functional theory (DFT) calculations.
- Han, Qi,Huang, Jia-Ying,Ji, Hong-Bing,Liu, Xiao-Hui,Tao, Lei-Ming,Xue, Can,Yu, Hai-Yang,Zhou, Xian-Tai,Zou, Wen
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supporting information
p. 115 - 122
(2021/12/04)
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- Three New Polyoxoniobates Functioning as Different Oxidation Catalysts
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Three new multifunctional isopolyniobates based on {Nb24O72}, namely, [Cu(en)2]9.75[Cu(en)2(H2O)]4[KNb24O72H9.25]2·36.5H2O (1), [Cu(en)2][Cu(en)2(H2O)]12[Cu(en)2(H2O)2]3[KNb24O72H7(H2O)2]2·99H2O (2), and [K(H2O)4][Cu(en)2(H2O)2]5[Cu(en)2(H2O)]8.25[Cu(en)2]2[K0.5Nb24O72H7.75]2·115.31H2O (3) (en = ethylenediamine), were obtained and characterized by IR, powder X-ray diffraction, single-crystal diffraction analysis, etc. Single-crystal analyses of the three compounds shows that all their clusters exhibit the same bowl-shaped structure, while the different transition metal complexes (TMCs) make compounds 1-3 show three entirely different packing structures. The catalytic properties of the three compounds as catalysts for Rhodamine B (RhB) photocatalytic degradation, styrene oxidation, and oxygen evolution reaction (OER) have been assessed, and all the compounds have good catalytic effects on the three different catalytic processes.
- Cui, Xiao-Bing,Li, Guanghua,Zhang, Ting-Ting
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p. 3191 - 3201
(2021/05/29)
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- Iodine-Initiated Dioxygenation of Aryl Alkenes Using tert-Butylhydroperoxides and Water: A Route to Vicinal Diols and Bisperoxides
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An environment-friendly and efficient dioxygenation of aryl alkenes for the construction of vicinal diols has been developed in water with iodine as the catalyst and tert-butylhydroperoxides (TBHPs) as the oxidant. The protocol was efficient, sustainable, and operationally simple. Detailed mechanistic studies indicated that one of the hydroxyl groups is derived from water and the other one is derived from TBHP. Additionally, the bisperoxides could be obtained in good yields with iodine as the catalyst, Na2CO3 as the additive, and propylene carbonate as the solvent, instead.
- Gao, Xiaofang,Lin, Jiani,Zhang, Li,Lou, Xinyao,Guo, Guanghui,Peng, Na,Xu, Huan,Liu, Yi
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p. 15469 - 15480
(2021/11/16)
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- Facile synthesis of libraries of functionalized cyclopropanes and oxiranes using ionic liquids – A new approach to the classical Corey-Chaykovsky reaction
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The potential of [PAIM][NTf2]/BMIM-ILs as a base/solvent in the Corey-Chaykovsky reaction is demonstrated by the facile synthesis of libraries of functionalized cyclopropanes from enones and oxiranes from aldehydes and ketones, at room temperature in respectable isolated yields. To demonstrate their application, the synthesized epoxides were employed as substrates for the synthesis of a library of 2,3-disubstituted quinolines, using [BMIM(SO3H)][OTf]/[BMIM][PF6] as a catalyst/solvent. The potential for recycling/reuse of the IL solvents was also explored.
- Malunavar, Shruti S.,Sutar, Suraj M.,Prabhala, Pavankumar,Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Aridoss, Gopalakrishnan,Laali, Kenneth K.
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supporting information
(2021/09/13)
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- Kinetic resolution ofN-aryl β-amino alcoholsviaasymmetric aminations of anilines
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An efficient kinetic resolution ofN-aryl β-amino alcohols has been developedviaasymmetricpara-aminations of anilines with azodicarboxylates enabled by chiral phosphoric acid catalysis. Broad substrate scope and high kinetic resolution performances were afforded with this method. Control experiments supported the critical roles of the NH and OH group in these reactions.
- Guo, Zheng,Xie, Jinglei,Hu, Tao,Chen, Yunrong,Tao, Houchao,Yang, Xiaoyu
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supporting information
p. 9394 - 9397
(2021/09/22)
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- Rhodium-Catalyzed Regioselective Formal Hydroacylation of Vinyl Epoxides toward Esters Involving β-Carbon Cleavage
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Herein we disclose the first example of the formal hydroacylation reactions of vinyl epoxides with chelating aldehydes enabled by rhodium catalysis for the efficient construction of functionalized esters. Detailed investigations of the mechanistic pathway reveal that the presence of a 2-vinyl group is essential in contributing to the success of this regioselective reaction, which might proceed through β-carbon cleavage as the key procedure.
- Chang, Zhi-Xin,Gong, Fei-Yuan,Wang, Xiaodan,Zhang, Tongbo,Han, Junfen,Li, Hong-Shuang
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supporting information
p. 6084 - 6089
(2021/08/16)
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- Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide
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The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides various indispensable products and intermediates in a sustainable manner. While formyl functionalities typically undergo irreversible oxidations when activating an oxidant, an atropisomeric two-axis aldehyde capable of catalytic turnover was identified for high-yielding epoxidations of cyclic and acyclic alkenes. The relative configuration of the stereogenic axes of the catalyst and the resulting proximity of the aldehyde and backbone residues resulted in high catalytic efficiencies. Mechanistic studies support a non-radical alkene oxidation by an aldehyde-derived dioxirane intermediate generated from hydrogen peroxide through the Payne and Criegee intermediates.
- Kokotos, Christoforos G.,Kokotou, Maroula G.,Lotter, Dominik,Sparr, Christof,Triandafillidi, Ierasia
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p. 10191 - 10196
(2021/08/12)
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- Self-assembled ionic liquid based organosilica-titania: A novel and efficient catalyst for green epoxidation of alkenes
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A novel titanium-containing self-assembled ionic liquid based hybrid organic-inorganic organosilica (Ti-ILOS) was prepared, characterized and applied as highly effective catalyst for the green epoxidation of alkenes in the presence of hydrogen peroxide as
- Yari, Omolbanin,Elhamifar, Dawood,Shaker, Masoumeh
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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supporting information
p. 519 - 526
(2021/03/31)
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- Preparation method of styrene oxide
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The invention discloses a preparation method of styrene oxide. Styrene is used as an initial raw material, and is subjected to bromination and saponification to obtain styrene oxide. According to the method, hydrogen peroxide is used as a main oxidant, and a hydrogen peroxide/sodium chlorate mixed oxidant is adopted, so that the situation that sodium chlorate is too strong in oxidability, and a large amount of phenyl-1, 2-dibromoethane, acetophenone and benzaldehyde byproducts are generated is avoided; in addition, a catalyst is added in the bromination process, so that the selectivity is improved, and the generation of phenyl glycol is reduced; the method is simple and convenient to operate, high in selectivity, few in side reaction, high in yield, high in product purity and suitable for domestic industrial production. The total yield reaches 89.0% or above, and the product purity reaches 99.0% or above.
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Paragraph 0017; 0037-0042
(2021/06/06)
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- A General Method for the Dibromination of Vicinal sp3C-H Bonds Exploiting Weak Solvent-Substrate Noncovalent Interactions
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A general procedure of 1,2-dibromination of vicinal sp3 C-H bonds of arylethanes using N-bromosuccinimide as the bromide reagent without an external initiator has been established. The modulation of the strength of the intermolecular noncovalent interactions between the solvent and arylethane ethanes, quantitatively evaluated via quantum chemical calculations, allows us to circumvent the fact that arylethane ethane cannot be dibrominated through traditional methods. The mechanism was explored by both experiments and quantum chemical calculations, revealing a radical chain with HAA process.
- Qi, Zaojuan,Li, Weihe,Niu, Yanning,Benassi, Enrico,Qian, Bo
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supporting information
p. 2399 - 2404
(2021/03/03)
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- Modification of MnFe2O4 surface by Mo (VI) pyridylimine complex as an efficient nanocatalyst for (ep)oxidation of alkenes and sulfides
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In this current paper, we report a new type of heterogeneous molybdenum (+6) complex, prepared by covalent grafting of cis-dioxo?molybdenum (VI) pyridylimine complex on the surface of MnFe2O4 nanoparticles (NP) and characterized using various physicochemical techniques. The recyclable prepared nanocatalyst was tested for sulfoxidation of sulfides and epoxidation of alkenes under solvent-free condition. The catalyst exhibited high turnover frequency for the oxidization of cyclooctene and cyclohexene (10,850 h?1) and thioanisole and dimethyl sulfide (41,250 h?1). The synthesized catalyst was found highly efficient, retrievable and eco-friendly catalyst for the (ep)oxidation of alkenes and sulfides in excellent yields in a short time. Furthermore, the synthesized nanocatalyst can be reused for four runs without apparent loss of its catalytic activity in the oxidation reaction.
- Bouzari, Narges,Bezaatpour, Abolfazl,Babaei, Behnam,Amiri, Mandana,Boukherroub, Rabah,Szunerits, Sabine
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- Anchoring of a terpyridine-based Mo(VI) complex on manganese ferrite as a recoverable catalyst for epoxidation of olefins under solvent-free conditions
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A magnetically separable heterogeneous nanocatalyst was obtained by anchoring a terpyridine-based Mo(VI) complex on modified MnFe2O4 nanoparticles and characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and diffuse reflectance spectroscopies (DRS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis. The catalytic activity of the supported molybdenum based catalyst was evaluated in the selective epoxidation of various olefins (cyclooctene, limonene, 1-dodecane, 1-heptene, styrene, 1-indene, α-pinene, cyclohexene) with tert-butyl hydroperoxide (TBHP) as an oxidant under solvent-free conditions. This nanocatalyst was easily separated by using an external magnetic field and reused consecutively at least five times with no significant loss in selectivity and catalytic activity. The short reaction time, simple preparation, high conversion, good physicochemical stability and magnetic recycling of the catalysts are beneficial.
- Fadaei Sarabi, Mahsa,Bezaatpour, Abolfazl,Mahmoudi, Ali
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p. 1597 - 1612
(2021/03/29)
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- Synthesis, structure, magnetic and catalytic competency of a tetradentate (nnoo) schiff base mediated dimeric copper(ii) complex
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One dinuclear copper(II) complex {μ-[2,2 -{ethane-1,2-diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}-{μ-[2,2 -{ethane-1,2- diylbis[(azanylylidene)methanylylidene]}bis(phenolato)]}dicopper(II), [Cu2(salen)2] (1) [salen2- = [2,2 -{ethane-1,2-diylbis- [(azanylylidene)methanylylidene]}bis(phenolato)] has been isolated and characterized by X-ray diffraction analysis and spectroscopic studies. X-ray single crystal structure examination revealed that each Cu(II) center in the asymmetric unit of 1 adopts a distorted square planar geometry with a CuN2O2 chromophore, where two asymmetric units are attached through congregation of Salen involving Cu-O bond to form dinuclear molecular unit [Cu2(salen)2]. In crystalline state, these dinuclear entities in 1 are extended through C-H π interactions and π π interactions displaying a 3D network structure. The variable-temperature magnetic susceptibility measurement asserted a dominant antiferromagnetic interaction between the copper(II) centers through Cu-O-Cu linkage in 1 with J = -1.46 cm-1. The catalytic efficacy of complex 1 was studied in a series of solvents for the oxidation of styrene and cyclooctene using tert-butyl-hydroperoxide (TBHP) as an active oxidant under mild conditions. The catalytic reaction mixture has been analyzed by gas chromatography and it displayed that the yield of the epoxidation and its selectivity is optimum in acetonitrile medium.
- CHOWDHURY, HABIBAR,BERA, RAJESH,ADHIKARY, CHANDAN
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p. 1280 - 1286
(2021/06/09)
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- Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions
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Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert-butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.
- McCaffrey, Vanessa P.,Conover, Olivia Q.,Bernard, Michael A.,Yarranton, Jonathan T.,Lessnau, Nicholas R.,Hempfling, Jordan P.
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- Efficient, Solvent Free and Selective Oxidation of Styrene to Benzaldehyde Over Niobium Modified Phosphomolybdic Acid Catalyst
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Niobium substituted phosphomolybdic acid with various Nb/P mole ratio of catalysts were successfully synthesised by hydrothermal method. These materials were characterized by X-ray diffraction, FT-IR spectroscopy, Raman spectroscopy, temperature programme
- Chary, Komandur V. R.,Viswanadham, Balaga
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- Preparation of zeolitic bismuth vanadomolybdate using a ball-shaped giant polyoxometalate for olefin epoxidation
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Zeolitic octahedral metal oxides are interesting materials that have received increasing attention. A bismuth vanadomolybdate-based zeolitic octahedral metal oxide was synthesized using a ball-shaped polyoxovanadomolybdate with different Bi sources. The material was used as a heterogeneous catalyst for olefin epoxidation. Different olefins were converted to their corresponding epoxides by the catalyst under mild conditions. This robust catalyst was reused several times without loss of activity.
- Hara, Michikazu,Li, Denan,Li, Yanshuo,Ueda, Wataru,Zhang, Zhenxin,Zhu, Qianqian
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p. 21624 - 21630
(2021/12/09)
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- Mono-copper substituted phosphotungstate supported on to neutral alumina: Synthesis, characterization and detailed studies for oxidation of styrene
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Mono-copper substituted phosphotungstate (PW11Cu) was supported on a neutral support (alumina) by wet impregnation method, which is the first instance of the use of alumina for supporting Transition metal substituted Polyoxometalates (TMSPOMs),
- Sadasivan, Rajesh,Patel, Anjali
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- Two new polyoxoniobosilicate-based compounds: Syntheses, structures, characterizations and their catalytic properties for epoxidation and water oxidation
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Two new polyoxoniobosilicates, Na12[Cu(en)2(H2O)2]5[H3(SiOH)2Si2Nb16O54]2·52H2O (1) and K4[Cu(en)2(H
- Zhang, Ting-Ting,Zhao, Zi-Qiu,Tian, Ge,Cui, Xiao-Bing
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- Aerobic oxidative C?C bond cleavage of aromatic alkenes by a high valency iron-containing perovskite catalyst
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High valency iron-containing perovskite catalyst BaFeO3-dcould efficiently promote the additive-free oxidative C?C bond cleavage of various aromatic alkenes to the corresponding aldehydes or ketones using O2as the sole oxidant. This system was applicable to the gram-scale oxidation of 1,1-diphenylethylene, in which 2.71 g (75% yield) of the analytically pure ketone could be isolated.
- Shibata, Satomi,Kamata, Keigo,Hara, Michikazu
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p. 2369 - 2373
(2021/04/22)
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- Nonheme manganese(III) complexes for various olefin epoxidation: Synthesis, characterization and catalytic activity
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Three mononuclear imine-based non-heme manganese(III) complexes with tetradentate ligands which have two deprotonated phenolate moieties, ([(X2saloph)Mn(OAc)(H2O)], 1a for X = Cl, 1b for X = H, and 1c for X = CH3, saloph = N,N-o-phenylenebis(salicylidenaminato)), were synthesized and characterized by 1H NMR, 13C NMR, ESI-Mass and elemental analysis. MnIII complexes catalysed efficiently various olefin epoxidation reactions with meta-chloroperbenzoic acid (MCPBA) under the mild condition. MnIII complexes 1a and 1c with the electron-withdrawing group -Cl and electron-donating group –CH3 showed little substituent effect on the epoxidation reactions. Product analysis, Hammett study and competition experiments with cis- and trans-2-octene suggested that MnIV = O, MnV = O, and MnIII-OOC(O)R species might be key oxidants in the epoxidation reaction under this catalytic system. In addition, the use of PPAA as a mechanistic probe demonstrated that Mn-acylperoxo intermediate (MnIII-OOC(O)R) 2 generated from the reaction of peracid with manganese complexes underwent both the heterolysis and the homolysis to produce MnV = O (3) or MnIV = O species (4). Moreover, the MnIII-OOC(O)R 2 species could react directly with the easy-to-oxidize substrate to give epoxide, whereas the species 2 might not be competent to the difficult-to-oxidize substrate for the epoxidation reaction.
- Lee, Sojeong,Park, Soyoung,Lee, Myoung Mi,Lee, Jiyoung,Kim, Cheal
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- Proton Switch in the Secondary Coordination Sphere to Control Catalytic Events at the Metal Center: Biomimetic Oxo Transfer Chemistry of Nickel Amidate Complex
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High-valent metal-oxo species are key intermediates for the oxygen atom transfer step in the catalytic cycles of many metalloenzymes. While the redox-active metal centers of such enzymes are typically supported by anionic amino acid side chains or porphyrin rings, peptide backbones might function as strong electron-donating ligands to stabilize high oxidation states. To test the feasibility of this idea in synthetic settings, we have prepared a nickel(II) complex of new amido multidentate ligand. The mononuclear nickel complex of this N5 ligand catalyzes epoxidation reactions of a wide range of olefins by using mCPBA as a terminal oxidant. Notably, a remarkably high catalytic efficiency and selectivity were observed for terminal olefin substrates. We found that protonation of the secondary coordination sphere serves as the entry point to the catalytic cycle, in which high-valent nickel species is subsequently formed to carry out oxo-transfer reactions. A conceptually parallel process might allow metalloenzymes to control the catalytic cycle in the primary coordination sphere by using proton switch in the secondary coordination sphere.
- Kim, Soohyung,Jeong, Ha Young,Kim, Seonghan,Kim, Hongsik,Lee, Sojeong,Cho, Jaeheung,Kim, Cheal,Lee, Dongwhan
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supporting information
p. 4700 - 4708
(2021/02/12)
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- Enthalpy-Entropy Compensation Effect in Oxidation Reactions by Manganese(IV)-Oxo Porphyrins and Nonheme Iron(IV)-Oxo Models
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"Enthalpy-Entropy Compensation Effect"(EECE) is ubiquitous in chemical reactions; however, such an EECE has been rarely explored in biomimetic oxidation reactions. In this study, six manganese(IV)-oxo complexes bearing electron-rich and -deficient porphyrins are synthesized and investigated in various oxidation reactions, such as hydrogen atom transfer (HAT), oxygen atom transfer (OAT), and electron-transfer (ET) reactions. First, all of the six Mn(IV)-oxo porphyrins are highly reactive in the HAT, OAT, and ET reactions. Interestingly, we have observed a reversed reactivity in the HAT and OAT reactions by the electron-rich and -deficient Mn(IV)-oxo porphyrins, depending on reaction temperatures, but not in the ET reactions; the electron-rich Mn(IV)-oxo porphyrins are more reactive than the electron-deficient Mn(IV)-oxo porphyrins at high temperature (e.g., 0 °C), whereas at low temperature (e.g., -60 °C), the electron-deficient Mn(IV)-oxo porphyrins are more reactive than the electron-rich Mn(IV)-oxo porphyrins. Such a reversed reactivity between the electron-rich and -deficient Mn(IV)-oxo porphyrins depending on reaction temperatures is rationalized with EECE; that is, the lower is the activation enthalpy, the more negative is the activation entropy, and vice versa. Interestingly, a unified linear correlation between the activation enthalpies and the activation entropies is observed in the HAT and OAT reactions of the Mn(IV)-oxo porphyrins. Moreover, from the previously reported HAT reactions of nonheme Fe(IV)-oxo complexes, a linear correlation between the activation enthalpies and the activation entropies is also observed. To the best of our knowledge, we report the first detailed mechanistic study of EECE in the oxidation reactions by synthetic high-valent metal-oxo complexes.
- Guo, Mian,Zhang, Jisheng,Zhang, Lina,Lee, Yong-Min,Fukuzumi, Shunichi,Nam, Wonwoo
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supporting information
p. 18559 - 18570
(2021/11/22)
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- Reaction pathways and deactivation mechanisms of isostructural Cr and Fe MIL-101 during liquid-phase styrene oxidation by hydrogen peroxide
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Isostructural Cr and Fe nanoporous MIL-101, synthesized without mineralizing agents, are investigated for styrene oxidation utilizing aqueous hydrogen peroxide to yield valuable oxygenates for chemical synthesis applications. Styrene conversion rates and oxygenate product distributions both depend on metal identity, as MIL-101(Fe) is more reactive for total styrene oxidation and is more pathway selective, preferring aldehyde (benzaldehyde) formation at the α-carbon to the aromatic ring, where MIL-101(Cr) sustains epoxide (styrene oxide) production at the same α-carbon. These pathways often involve hydrogen peroxide derived radical intermediates (O, -HOO, -HO-) and metallocycle transition states. We postulate that the higher reactivity of one of these surface intermediates, Fe(iv)O relative to Cr(iv)O, leads to higher styrene oxidation rates for MIL-101(Fe), while higher electrophilicity of Cr(iii)-OOH intermediates translates to the higher styrene oxide selectivity observed for MIL-101(Cr). Secondary styrene oxide and benzaldehyde conversions are observed over both analogs, but the former is more prevalent over MIL-101(Fe) due to higher Lewis/Br?nsted acid site density and strength compared to MIL-101(Cr). Recyclability experiments combined with characterization via XRD, SEM/EDXS, and FT-IR and UV-vis spectroscopies show that the nature of MIL-101(Fe) sites does not change significantly with each cycle, whereas MIL-101(Cr) suffers from metal leaching, which impacts styrene conversion rates and product distribution. Both catalysts require active site regeneration, though MIL-101(Fe) sites are more susceptible to reactivation, even under mild conditions. Finally, examination of styrene conversion for three unique synthesized phases of MIL-101(Cr) rationalizes that nodal defects are largely responsible for observed reactivity and selectivity but predispose the framework to metal leaching as a predominant deactivation mechanism.
- Sarazen, Michele L.,Yang, Rachel A.
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p. 5282 - 5296
(2021/08/16)
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- Evaluation of the protolytic equilibria and catalytic activity of sugar-based Schiff base ligands with VO2+ and MoO22+ cations in sulfoxidation and epoxidation reactions
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Based on the two anomeric methyl 3-amino-2,3-dideoxy-D-arabino-hexopyranosides ten new sugar-modified Schiff base ligands have been synthesized after monocondensation reaction with five o-hydroxyaromatic aldehydes, i.e. salicylaldehyde and its five para-s
- Chylewska, Agnieszka,D?browska, Aleksandra,Karman, Marta,Madejska, Katarzyna,Romanowski, Grzegorz
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- Catalytic alcohol oxidation using cationic Schiff base manganeseIII complexes with flexible diamino bridge
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Four Schiff base manganese(III) complexes with derivatives of [(R,R)-N,N’-bis(salicy1idene)-1,2-cyclohexanediaminato)] including substituents on salicylaldehyde such as 3-methoxy, 3,5-di-tert-butyl and 3,5-chloro were synthesized and characterized using a combination of IR, UV–Vis, and HR ESI-MS techniques. The catalytic activity of these complexes was tested in the oxidation of 1-phenylethanol to acetophenone, revealing very good performances for all of the four manganese complexes. The catalytic reactions were carried out in the presence of tert-butyl hydroperoxide (TBHP) as oxidant and imidazole as co-catalyst. Complex Mn-4, bearing electron withdrawing [(R,R)-N,N’-bis(3,5-di-chloro-salicylidene)-1,2-cyclohexanediaminato)] ligand was found to be the most stable of the tested Mn(III) complexes and was selected for the oxidation of several primary and secondary alcohols.
- Kakavand, Meysam,Mastrorilli, Piero,Mesto, Ernesto,Neshat, Abdollah,Osanlou, Farzane,Schingaro, Emanuela,Todisco, Stefano
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- Alkene, Bromide, and ROH – How To Achieve Selectivity? Electrochemical Synthesis of Bromohydrins and Their Ethers
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Bromohydrins and their ethers were electrochemically synthesized via hydroxy- and alkoxybromination of alkenes using potassium bromide and water or alcohols. High selectivity of bromohydrins formation was achieved only with the use of DMSO as the solvent and an acid as the additive. The proposed combination of starting reagents, additives, and solvents allowed to form bromohydrins or their ethers selectively despite the variety of side-products (epoxides, dibromides, diols). Bromohydrins were obtained in high yields, up to 96%, with a broad substrate scope in an undivided electrochemical cell equipped with glassy carbon and platinum electrodes at high current density. (Figure presented.).
- Bityukov, Oleg V.,Nikishin, Gennady I.,Terent'ev, Alexander O.,Vil', Vera A.
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supporting information
p. 3070 - 3078
(2021/05/10)
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- Controlling product selectivity with nanoparticle composition in tandem chemo-biocatalytic styrene oxidation
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The combination of heterogeneous catalysis and biocatalysis into one-pot reaction cascades is a potential approach to integrate enzymatic transformations into existing chemical infrastructure. Peroxygenases, which can achieve clean C-H activation, are ideal candidates for incorporation into such tandem systems, however a constant supply of low-level hydrogen peroxide (H2O2) is required. The use of such enzymes at industrial scale will likely necessitate thein situgeneration of the oxidant from cheap and widely available reactants. We show that combing heterogeneous catalysts (AuxPdy/TiO2) to produce H2O2in situfrom H2and air, in the presence of an evolved unspecific peroxygenase fromAgrocybe aegerita(PaDa-I variant) yields a highly active cascade process capable of oxidizing alkyl and alkenyl substrates. In addition, the tandem process operates under mild reaction conditions and utilizes water as the only solvent. When alkenes such as styrene are subjected to this tandem oxidation process, divergent reaction pathways are observed due to the competing hydrogenation of the alkene by palladium rich nanoparticles in the presence of H2. Each pathway presents opportunities for value added products. Product selectivity was highly sensitive to the rate of reduction compared to hydrogen peroxide delivery. Here we show that some control over product selectivity may be exerted by careful selection of nanoparticle composition.
- Alcalde, Miguel,Brehm, Joseph,Davies, Thomas E.,Freakley, Simon J.,Harrison, Susan T. L.,Hutchings, Graham J.,Kotsiopoulos, Athanasios,Lewis, Richard J.,Morgan, David J.,Opperman, Diederik J.,Smit, Martha S.,Wilbers, Derik,van Marwijk, Jacqueline
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p. 4170 - 4180
(2021/06/17)
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- Dendrimer crown-ether tethered multi-wall carbon nanotubes support methyltrioxorhenium in the selective oxidation of olefins to epoxides
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Benzo-15-crown-5 ether supported on multi-wall carbon nanotubes (MWCNTs) by tethered poly(amidoamine) (PAMAM) dendrimers efficiently coordinated methyltrioxorhenium in the selective oxidation of olefins to epoxides. Environmentally friendly hydrogen peroxide was used as a primary oxidant. Up to first and second generation dendrimer aggregates were prepared by applying a divergent PAMAM methodology. FT-IR, XRD and ICP-MS analyses confirmed the effective coordination of methyltrioxorhenium by the benzo-15-crown-5 ether moiety after immobilization on MWCNTs. The novel catalysts converted olefins to the corresponding epoxides in high yield without the use of Lewis base additives, or anhydrous hydrogen peroxide, the catalyst being stable for more than six oxidative runs. In the absence of the PAMAM structure, the synthesis of diols largely prevailed.
- Bizzarri, Bruno Mattia,Botta, Lorenzo,Crucianelli, Marcello,Fanelli, Angelica,Ferella, Francesco,Gontrani, Lorenzo,Sadun, Claudia,Saladino, Raffaele
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p. 17185 - 17194
(2020/05/18)
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- Organomagnesium Based Flash Chemistry: Continuous Flow Generation and Utilization of Halomethylmagnesium Intermediates
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The generation of highly unstable chloromethylmagnesium chloride in a continuous flow reactor and its reaction with aldehydes and ketones is reported. With this strategy, chlorohydrins and epoxides were synthesized within a total residence time of only 2.6 s. The outcome of the reaction can be tuned by simply using either a basic or an acidic quench. Very good to excellent isolated yields, up to 97%, have been obtained for most cases (30 examples).
- Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 7537 - 7541
(2020/10/12)
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- The first crystallographically characterised ruthenium(vi) alkylimido porphyrin competent for aerobic epoxidation and hydrogen atom abstraction
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The syntheses of [RuVI(Por)(NAd)(O)] and [RuVI(2,6-F2-TPP)(NAd)2] have been described. [RuVI(2,6-F2-TPP)(NAd)(O)] capable of catalysing aerobic epoxidation of alkenes has been characterised by X-ray crystallography with RuNAd and RuO bond distances being 1.778(5) ? and 1.760(4) ? (∠O-Ru-NAd: 174.37(19)°), respectively. Its first reduction potential is 740 mV cathodically shifted from that of [RuVI(2,6-F2-TPP)(O)2].
- Chang, Xiao-Yong,Che, Chi-Ming,Shing, Ka-Pan,Wan, Qingyun
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supporting information
p. 4428 - 4431
(2020/05/05)
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- Schiff base Cu( II) complex with binaphthalene diamine as skeleton and preparation method thereof (by machine translation)
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The Schiff base Cu( II) complex catalyst, takes the binaphthalene diamine as the raw material, and condensation of the series of substituted salicylaldehyde to obtain Schiff base, complex catalyst, and the Schiff base ligand, ligand and the copper salt reaction Cu( II) are used for catalyzing olefin epoxidation . and the preparation method Cu( II) comprises the following steps of: cheap and easily available, catalytic activity, and obtained epoxidation products of various olefin epoxidation products . The invention further discloses a Schiff base complex catalyst containing the binaphthalene diamine as, a skeleton. (by machine translation)
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Paragraph 0080-0084
(2020/06/02)
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- Oxidovanadium(V) and dioxidomolybdenum(VI) Complexes of N'-(3,5-Dichloro-2-hydroxybenzylidene)-4-fluorobenzohydrazide: Synthesis, characterization, crystal structures and catalytic property
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N'-(3,5-Dichloro-2-hydroxybenzylidene)-4-fluorobenzohydrazide (H2L) was used to prepare oxidovanadium(V) complex [VOL(OEt)(MeOH)] (1) and dioxidomolybdenum(VI) complex [MoO2L(OH2)]·[MoO2L(EtOH)] (2). The complexes were characterized by IR, UV-Vis, NMR spectroscopy, and single crystal X-ray diffraction. X-ray analysis indicates that the complexes are mononuclear species with the metal atoms in octahedral coordination. The complexes were studied for catalytic oxidation property on some olefins with tert-butyl hydroperoxide as oxidant.
- Liu, Huan-Yu,Yang, Luo-Ju,Ye, Ya-Fang,Yin, Yi-Shu,Zou, Xiao-Ling
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p. 130 - 136
(2020/03/30)
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- Rare earth metal compound, preparation method, composition, and method for catalyzing epoxidation of olefin
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The invention relates to a rare earth metal compound and application thereof in catalyzing epoxidation of olefin. The rare earth metal compound disclosed by the invention has a structure as shown in aformula E. The invention also relates to a preparation method of the rare earth metal compound and a composition containing the rare earth metal compound. The method is characterized in that a rare earth metal compound is added into the reaction, so that the dosage of a molybdenum catalyst can be reduced. Olefin and organic peroxide react under the action of a catalyst to generate epoxide, the organic peroxide is converted into corresponding alcohol, and the conversion rate of the organic peroxide is larger than 99%. After the reaction is finished, the rare earth metal compound can be separated and recycled. The method has the advantages of simple process, high catalytic system activity, effective reduction of the use amount of the catalyst while guaranteeing the catalytic efficiency, andcost saving.
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Paragraph 0084-0085
(2020/07/24)
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- Kinetic Relationships of Liquid-Phase Oxidation of Styrene with Hydrogen Peroxide in the Presence of Polyoxotungstate Modified with Cerium Cations
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Liquid-phase oxidation of styrene with hydrogen peroxide in the presence of a catalytic system based on (NH4)10W12O41 + Ce(NO3)3 + H3PO4, supported on a microstructured carbon material and treated with an aqueous Н2О2 solution, was evaluated. The major reaction products are phenyloxirane and benzaldehyde, with phenylacetaldehyde, 1-phenylethane-1,2-diol, and benzoic acid also present. The kinetic relationships of the process were investigated, and a kinetic model according to which phenyloxirane is the primary reaction product was suggested. Aldehydes were accumulated by parallel routes, namely oxidation of phenyloxirane and of its hydrolysis product, 1-phenylethane-1,2-diol. With an increase in the styrene, Н2О2 molar ratio, oxidation of 1-phenylethane-1,2-diol became the major pathway of the aldehyde formation.
- Alimardanov, H. M.,Garibov, N. I.,Musayeva, E. S.,Veliyeva, F. M.
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p. 729 - 740
(2020/07/03)
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- Ionic liquids vs conventional solvents: A comparative study in the selective catalytic oxidations promoted by oxovanadium(IV) complexes
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Two oxovanadium(IV) complexes containing 4-acyl-5-pyrazolonate-κ2-O,O' bidentate ligands with different chain lengths in the acyl moiety, namely HQC6 (complex I) and HQC17 (complex II), have been synthetized and full characterized, to study their catalytic activity toward the mild and selective oxidation of olefins or model organosulphur substrates, promoted by H2O2 or tert-butyl hydroperoxide (TBHP). The influence due to the type of solvent, likewise ionic liquids (ILs) or conventional medium, was analysed. H2O2 has proven less efficient, in comparison to TBHP. Quantum-chemical calculations have shown that, the key catalytic species involved and, consequently, the actual mechanism might be slightly different according to the oxidant used, i.e. the peroxo VO(QMe)(O2) adduct in the case of H2O2 and the tert-butylperoxo VO(QMe)2(OOt-Bu) adduct in the case of TBHP. Preliminary calculations suggested that, in ionic liquids, the VO(QMe)2 complex might reveal relatively unstable, hence qualitatively explaining the moderate efficiency observed in these media.
- Aschi, Massimiliano,Campitelli, Patrizio,Crucianelli, Marcello,Di Nicola, Corrado,Marchetti, Fabio,Pettinari, Riccardo
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- Double end-on azido derivative of a tridentate (NNO) Schiff base dimeric copper(II) complex: synthesis, X-ray structure, magnetic property and catalytic effectiveness
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A dimeric copper(II) complex, bis{(2-[1-(aminoethylimino)ethyl]-phenoxo}-di-μ1,1-azido-dicopper(II), [Cu2(L)2(μ2-1,1-N3)2] (1) [L = 2-[1-(aminoethylimino)ethyl]-phenoxo ion], has been isolated using a self-assembly reaction using a 1:1:1 molar ratio of Cu(NO3)2·3H2O, HL and NaN3 in methanol at room temperature and characterized through X-ray diffraction analysis and spectroscopic studies. X-ray structural analysis reveals that 1 consists of two distinct dinuclear molecular units, where each copper(II) center in the individual dinuclear unit adopts a distorted square pyramidal geometry with a CuN4O chromophore ligated through a tridentate (NNO) Schiff base and two N atoms of two different bridging azides in μ1,1-mode. Two Cu(II) centers are linked through double μ2-1,1-N3 bridges to form the dinuclear unit [Cu2(L)2(μ2-1,1-N3)2]. In the crystalline state, the dinuclear units in 1 are associated through weak intermolecular N-H?O hydrogen bonds to afford a 2-D sheet structure viewed along the crystallographic a-axis. The small magnitude of the antiferromagnetic interaction (J = –0.45 cm?1) is a result of the long Cu···Cu separation (3.205(2) ?). The catalytic efficacy of 1 was studied in a series of solvents for the epoxidation of alkenes using tert-butyl-hydroperoxide (TBHP) as an efficient oxidant under mild conditions.
- Chowdhury, Habibar,Bera, Rajesh,Rizzoli, Corrado,Adhikary, Chandan
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p. 3062 - 3078
(2020/10/29)
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- Partial and full β-bromination of meso-tetraphenylporphyrin: Effects on the catalytic activity of the manganese and nickel complexes for photo oxidation of styrene in the presence of molecular oxygen and visible light
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A series of β-brominated meso-tetraphenylporphyrins, H2TPPBrx (x = 0, 4, 8) have been synthesized and the photocatalytic activity of their manganese (III) and nickel (II) complexes in photo oxidation of styrene was thoroughly investi
- Esfandiar, Milad,Saadati, Saeedeh
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- Chiral cis-dioxidomolybdenum(VI) complexes with Schiff bases possessing two alkoxide groups: Synthesis, structure, spectroscopic studies and their catalytic activity in sulfoxidation and epoxidation
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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?
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Spatially Ordered Arrangement of Multifunctional Sites at Molecule Level in a Single Catalyst for Tandem Synthesis of Cyclic Carbonates
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With fossil energy resources increasingly drying up and gradually causing serious environmental impacts, pursuing a tandem and green synthetic route for a complex and high-value-Added compound by using low-cost raw materials has attracted considerable attention. In this regard, the selective and efficient conversion of light olefins with CO2 into high-value-Added organic cyclic carbonates (OCCs) is of great significance owing to their high atom economy and absence of the isolation of intermediates. To fulfill this expectation, a multifunctional catalytic system with controllable spatial arrangement of varied catalytic sites and stable texture, in particular, within a single catalyst, is generally needed. Here, by using a stepwise electrostatic interaction strategy, imidazolium-based ILs and Au nanoparticles (NPs) were stepwise immobilized into a sulfonic group grafted MOF to construct a multifunctional single catalyst with a highly ordered arrangement of catalytic sites. The Au NPs and imidazolium cation are separately responsible for the selective epoxidation and cycloaddition reaction. The mesoporous cage within the MOF enriches the substrate molecules and provides a confined catalytic room for the tandem catalysis. More importantly, the highly ordered arrangement of the varied active sites and strong electrostatic attraction interaction result in the intimate contact and effective mass transfer between the catalytic sites, which allow for the highly efficient (>74% yield) and stable (repeatedly usage for at least 8 times) catalytic transformation. The stepwise electrostatic interaction strategy herein provides an absolutely new approach in fabricating the controllable multifunctional catalysts, especially for tandem catalysis.
- Chang, Gang-Gang,Chen, Jian,Huang, Ke-Xin,Ke, Shan-Chao,Li, Jia-Xin,Luo, Ting-Ting,Ma, Xiao-Chen,Wu, Jian,Yang, Xiao-Yu
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- Syntheses, characterization and properties of two new dodeca-niobates presenting unprecedented features
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Two new dodeca-niobate materials, K3[Nb2O2][H7SiNb12O40]·16H2O (1) and [Cu(en)2]9[(VNb12V1.69Nb0.31O42en0.3
- Cui, Xiao-Bing,Lin, Po-Han,Yu, Gui-Yang,Zhang, Ting-Ting,Zhang, Xiao
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p. 6495 - 6503
(2020/06/03)
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- Epoxidation of Alkenes with Molecular Oxygen as the Oxidant in the Presence of Nano-Al 2O 3
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The nano-Al 2O 3-promoted epoxidation of alkenes with molecular oxygen as the oxidant has been developed, providing an efficient route to a variety of epoxides in moderate to excellent yields. The environmentally friendly and efficient nano-Al 2O 3catalyst could be easily recovered and reused five times without significant loss of activity.
- Zhou, Xuan,Wang, Qiong,Xiong, Wenfang,Wang, Lu,Ye, Rongkai,Xiang, Ge,Qi, Chaorong,Hu, Jianqiang
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supporting information
p. 1789 - 1794
(2020/09/18)
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- Cu(ii)Cl2containing bispyridine-based porous organic polymer support preparedviaalkyne-azide cycloaddition as a heterogeneous catalyst for oxidation of various olefins
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A new type of porous organic polymer (POP) based heterogeneous catalystCu-POPwas prepared by immobilizing Cu(ii)Cl2into bpy containing POP preparedviaalkyne-azide cycloaddition. This new catalyst showed efficient catalytic activities and outstanding reusability. Remarkably, one batch ofCu-POPwas continuously used for all olefins without losing its activity by simply washing.
- Choi, Hye Min,Lee, Suk Joong,Yoon, Jongho
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supporting information
p. 9149 - 9152
(2020/06/17)
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- Oxoiron(v) mediated selective electrochemical oxygenation of unactivated C-H and CC bonds using water as the oxygen source
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An efficient electrochemical method for the selective oxidation of C-H bonds of unactivated alkanes (BDE ≤97 kcal mol-1) and CC bonds of alkenes using a biomimetic iron complex, [(bTAML)FeIII-OH2]-, as the redox mediator in an undivided electrochemical cell with inexpensive carbon and nickel electrodes is reported. The O-atom of water remains the source of O-incorporation in the product formed after oxidation. The products formed upon oxidation of C-H bonds display very high regioselectivity (75:1, 3°:2° for adamantane) and stereo-retention (RC ～99% for cyclohexane derivatives). The substrate scope includes natural products such as cedryl acetate and ambroxide. For alkenes, epoxides were obtained as the sole product. Mechanistic studies show the involvement of a high-valent oxoiron(v) species, [(bTAML)FeV(O)]- formed via PCET (overall 2H+/2e-) from [(bTAML)FeIII-OH2]- in CPE at 0.80 V (vs. Ag/AgNO3). Moreover, electrokinetic studies for the oxidation of C-H bonds indicate a second-order reaction with the C-H abstraction by oxoiron(v) being the rate-determining step.
- Chandra, Bittu,Gupta, Sayam Sen,Hellan, K. M.,Pattanayak, Santanu
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p. 11877 - 11885
(2020/11/18)
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- Magnetically recoverable porphyrin-based nanocatalysts for the effective oxidation of olefins with hydrogen peroxide: A comparative study
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In this paper, preparation, characterization and catalytic applications of metalloporphyrin-based magnetic nanocatalysts were investigated. meso-Tetrakis(4-carboxyphenyl)porphyrinatoiron(iii) chloride (Fe(TCPP)Cl) and meso-tetrakis(4-carboxyphenyl)porphyrinatomanganese(iii) acetate (Mn(TCPP)OAc) were separately immobilized onto the surface of amine functionalized magnetic nanoparticles (Fe3O4/SiO2/NH2) via covalent attachment. The obtained nanocatalysts were characterized using FT-IR and UV-Vis and atomic absorption spectroscopy, X-ray powder diffraction (XRD), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The catalytic efficiency of Fe3O4/SiO2/NH2-Fe(TCPP)Cl and Fe3O4/SiO2/NH2-Mn(TCPP)OAc for the green oxidation of alkenes with H2O2 was investigated in a comparative manner. The Mn-porphyrin based magnetic nanocatalyst shows higher catalytic efficiency compared to the Fe-porphyrin. In addition, the prepared magnetic nanocatalyst exhibited excellent reusability and could be reused at least five times without significant leaching or loss of activity. This journal is
- Rayati, Saeed,Moradi, Dana,Nejabat, Fatemeh
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p. 19385 - 19392
(2020/11/23)
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- Chemoselective Homologation-Deoxygenation Strategy Enabling the Direct Conversion of Carbonyls into (n+1)-Halomethyl-Alkanes
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The sequential installation of a carbenoid and a hydride into a carbonyl, furnishing halomethyl alkyl derivatives, is reported. Despite the employment of carbenoids as nucleophiles in reactions with carbon-centered electrophiles, sp3-type alkyl halides remain elusive materials for selective one-carbon homologations. Our tactic levers on using carbonyls as starting materials and enables uniformly high yields and chemocontrol. The tactic is flexible and is not limited to carbenoids. Also, diverse carbanion-like species can act as nucleophiles, thus making it of general applicability.
- Citarella, Andrea,Holzer, Wolfgang,Ielo, Laura,Langer, Thierry,Miele, Margherita,Pace, Vittorio,Urban, Ernst,Zehl, Martin
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supporting information
p. 7629 - 7634
(2020/10/12)
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