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Mechanistic insights into liquid-phase autoxidation of cyclohexene in acetonitrile. MOLECULAR CATALYSIS 2022. [DOI: 10.1016/j.mcat.2022.112367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Selective Oxofunctionalization of Cyclohexene over Titanium Dioxide-Based and Bismuth Oxyhalide Photocatalysts by Visible Light Irradiation. Catalysts 2020. [DOI: 10.3390/catal10121448] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Photocatalysis driven under visible light allows us to carry out hydrocarbon oxofunctionalization under ambient conditions, using molecular oxygen as a sacrificial reagent, with the absence of hazardous subproducts and the potential use of the Sun as a clean and low-cost source of light. In this work, eight materials—five based on titanium dioxide and three based on bismuth oxyhalides—were used as photocatalysts in the selective oxofunctionalization of cyclohexene. The cyclohexane oxofunctionalization reactions were performed inside of a homemade photoreactor equipped with a 400 W metal halide lamp and injected air as a source of molecular oxygen. In all assayed systems, the main oxygenated products, identified by mass spectrometry, were 1,2-epoxycyclohexane, 2-cyclohexen-1-ol, and 2-cyclohexen-1-one. Titanium dioxide-based materials exhibited higher selectivities for 1,2-epoxycyclohexane than bismuth oxyhalide-based materials. In addition to this, titanium dioxide doped with iron exhibited the best selectivity for 1,2-epoxycyclohexane, demonstrating that iron plays a relevant role in the cyclohexene epoxidation process.
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Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory. COMPUTATION 2020. [DOI: 10.3390/computation8020052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.
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Agasti N, Astle MA, Rance GA, Alves Fernandes J, Dupont J, Khlobystov AN. Cerium Oxide Nanoparticles Inside Carbon Nanoreactors for Selective Allylic Oxidation of Cyclohexene. NANO LETTERS 2020; 20:1161-1171. [PMID: 31975606 DOI: 10.1021/acs.nanolett.9b04579] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The confinement of cerium oxide (CeO2) nanoparticles within hollow carbon nanostructures has been achieved and harnessed to control the oxidation of cyclohexene. Graphitized carbon nanofibers (GNF) have been used as the nanoscale tubular host and filled by sublimation of the Ce(tmhd)4 complex (where tmhd = tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)) into the internal cavity, followed by a subsequent thermal decomposition to yield the hybrid nanostructure CeO2@GNF, where nanoparticles are preferentially immobilized at the internal graphitic step-edges of the GNF. Control over the size of the CeO2 nanoparticles has been demonstrated within the range of about 4-9 nm by varying the mass ratio of the Ce(tmhd)4 precursor to GNF during the synthesis. CeO2@GNF was effective in promoting the allylic oxidation of cyclohexene in high yield with time-dependent control of product selectivity at a comparatively low loading of CeO2 of 0.13 mol %. Unlike many of the reports to date where ceria catalyzes such organic transformations, we found the encapsulated CeO2 to play the key role of radical initiator due to the presence of Ce3+ included in the structure, with the nanotube acting as both a host, preserving the high performance of the CeO2 nanoparticles anchored at the GNF step-edges over multiple uses, and an electron reservoir, maintaining the balance of Ce3+ and Ce4+ centers. Spatial confinement effects ensure excellent stability and recyclability of CeO2@GNF nanoreactors.
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Affiliation(s)
- Nityananda Agasti
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Maxwell A Astle
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Graham A Rance
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
- Nanoscale and Microscale Research Centre (nmRC) , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Jesum Alves Fernandes
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
| | - Jairton Dupont
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
- Institute of Chemistry , Universidade Federal do Rio Grande do Sul , Avenida Bento Goncalves 9500 , BR-91501970 Porto Alegre , RS , Brazil
| | - Andrei N Khlobystov
- School of Chemistry , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
- Nanoscale and Microscale Research Centre (nmRC) , University of Nottingham , University Park, Nottingham NG7 2RD , United Kingdom
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Said MI, El-Said AI, Aly AAM, Abou-Taleb A. Ultrasound assisted facile synthesis of Mn(II) and Cu(II) coordination polymers and their use as precursors for α-Mn 3O 4 and CuO nanoparticles: Synthesis, characterization and catalytic properties. ULTRASONICS SONOCHEMISTRY 2018; 46:68-78. [PMID: 29739514 DOI: 10.1016/j.ultsonch.2018.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 04/02/2018] [Accepted: 04/07/2018] [Indexed: 05/09/2023]
Abstract
A self-assembly of pyridine-2,6-dicarboxylate with Cu(II) and Mn(II) under ultrasonic and microwave irradiation gave the two coordination polymers [Cu(PDA)(H2O)1.5]n (1) and [Mn(PDA)(H2O)1.5]n (2). Their structures were characterized using IR, elemental analysis, X-ray diffraction (XRD) and spectroscopic methods. The corresponding α-Mn3O4 and CuO nanoparticles were synthesized by calcination of 1 and 2 in air at 600 °C. Transmission electron microscopy (TEM) reveals a sphere-like morphology for the Mn3O4 nanoparticles. Shrinkage of the particle size from 90 nm (by conventional synthesis of the precursor) to 19 nm (ultrasonic-assisted) takes place, indicating the great effect of ultrasonication. CuO nanoparticles were of semispherical (conventional and ultrasonic-assisted methods) and hexagonal shapes (microwave irradiation) with an average diameter of 7, 15 and 25 nm, respectively. The catalytic performance of the coordination polymers towards degradation of methylene blue and methyl orange in the presence of hydrogen peroxide was studied. Using the same dose, catalyst 1 proved to be more efficient in color removal of both MB and MO than catalyst 2 did. Recycling test for 2 showed that it is a recyclable catalyst with no structural changes over three recycling experiments.
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Affiliation(s)
- Mohamed I Said
- Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt.
| | - Asma I El-Said
- Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt
| | - Aref A M Aly
- Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt
| | - Asia Abou-Taleb
- Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut, Egypt
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Kremer ML. Strong Inhibition of the Fe3+ + H2O2 Reaction by Ethanol: Evidence against the Free Radical Theory. PROGRESS IN REACTION KINETICS AND MECHANISM 2018. [DOI: 10.3184/146867817x14954764850496] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The effect of ethanol on the catalytic decomposition of H2O2 by Fe3+ was investigated. While expecting a simple competitive oxidation of C2H5OH, far more complex kinetics were encountered experimentally: already minute amounts of C2H5OH (1% of H2O2) had a powerful retardation effect on the disappearance of H2O2. This fact indicated the operation of an intricate mechanism. It excluded the possibility of OH• radicals being the active agents in the oxidation: OH• radicals generated by radiolysis react with C2H5OH with a very high rate constant. The interpretation of the experimental results was based on a mechanism involving iron in a +5 oxidation state (FeO3+) as the active intermediate and its binding in complex structures in which activity is reduced. The question of free radical versus non-radical mechanisms is discussed. The conclusions differ from generally accepted concepts in relation to the Fenton and related reactions.
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Affiliation(s)
- Eike B. Bauer
- University of Missouri - St. Louis; Department of Chemistry and Biochemistry; One University Boulevard St. Louis, MO 63121 USA
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Kirillova MV, Paiva PTD, Carvalho WA, Mandelli D, Kirillov AM. Mixed-ligand aminoalcohol-dicarboxylate copper(II) coordination polymers as catalysts for the oxidative functionalization of cyclic alkanes and alkenes. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2016-1012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractNew copper(II) catalytic systems for the mild oxidative C–H functionalization of cycloalkanes and cycloalkenes were developed, which are based on a series of mixed-ligand aminoalcohol-dicarboxylate coordination polymers, namely [Cu2(μ-dmea)2(μ-nda)(H2O)2]n·2nH2O (1), [Cu2(μ-Hmdea)2(μ-nda)]n·2nH2O (2), and [Cu2(μ-Hbdea)2(μ-nda)]n·2nH2O (3) that bear slightly different dicopper(II) aminoalcoholate cores, as well as on a structurally distinct dicopper(II) [Cu2(H4etda)2(μ-nda)]·nda·4H2O (4) derivative [abbreviations: H2nda, 2,6-naphthalenedicarboxylic acid; Hdmea, N,N′-dimethylethanolamine; H2mdea, N-methyldiethanolamine; H2bdea, N-butyldiethanolamine; H4etda, N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine]. Compounds 1–4 act as homogeneous catalysts in the three types of model catalytic reactions that proceed in aqueous acetonitrile medium under mild conditions (50–60°C): (i) the oxidation of cyclohexane by hydrogen peroxide to cyclohexyl hydroperoxide, cyclohexanol, and cyclohexanone, (ii) the oxidation of cycloalkenes (cyclohexene, cyclooctene) by hydrogen peroxide to a mixture of different oxidation products, and (iii) the single-pot hydrocarboxylation of cycloalkanes (cyclopentane, cyclohexane, cycloheptane, cyclooctane) by carbon monoxide, water, and a peroxodisulfate oxidant into the corresponding cycloalkanecarboxylic acids. The catalyst and substrate scope as well as some mechanistic features were investigated; the highest catalytic activity of 1–4 was observed in the hydrocarboxylation of cycloalkanes, allowing to achieve up to 50% total product yields (based on substrate).
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Affiliation(s)
- Marina V. Kirillova
- 1Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
| | - Polyana Tomé de Paiva
- 2Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Av. dos Estados, 5001, Bangu, Santo André, SP, Brazil
| | - Wagner A. Carvalho
- 2Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Av. dos Estados, 5001, Bangu, Santo André, SP, Brazil
| | - Dalmo Mandelli
- 2Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Av. dos Estados, 5001, Bangu, Santo André, SP, Brazil
| | - Alexander M. Kirillov
- 1Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal
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Yan Q, Fang YC, Jia YX, Duan XH. Chemoselective hydrogen peroxide oxidation of primary alcohols to aldehydes by a water-soluble and reusable iron(iii) catalyst in pure water at room temperature. NEW J CHEM 2017. [DOI: 10.1039/c6nj03793c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel, water-soluble and reusable FeCl3 catalyst showed high catalytic activity and chemoselectivity in the H2O2-oxidation of primary alcohols into aldehydes.
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Affiliation(s)
- Qi Yan
- College of Biological Sciences and Biotechnology
- Beijing Forestry University
- Beijing
- China
| | - Ye Chen Fang
- College of Biological Sciences and Biotechnology
- Beijing Forestry University
- Beijing
- China
| | - Yun Xue Jia
- College of Biological Sciences and Biotechnology
- Beijing Forestry University
- Beijing
- China
| | - Xin Hong Duan
- College of Science
- Beijing Forestry University
- Beijing
- China
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Li Q, Zhang L, Wang X, Xu G, Chen Y, Dai L. Color conversion of the magnetically separable Al/Fe oxide RNGO in the selective oxidation of benzyl alcohol induced the observation of its morphology change. RSC Adv 2017. [DOI: 10.1039/c7ra03527f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The morphology changed in accordance with the catalytic performance through the observation of color variation during the lifetime test: with a chaotic layout and a comparable inferior catalytic activity initially, while a waffle or pastry state and a relatively superior activity in the prime time performance.
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Affiliation(s)
- Qichen Li
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Lingling Zhang
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Xiaozhong Wang
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Gang Xu
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Yingqi Chen
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
| | - Liyan Dai
- Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology
- College of Chemical and Biological Engineering
- Zhejiang University
- Hangzhou 310027
- P. R. China
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A cis-dioxomolybdenum Schiff base complex: synthesis, crystal structure and catalytic activity in oxidation of olefins using hydrogen peroxide. TRANSIT METAL CHEM 2015. [DOI: 10.1007/s11243-015-9985-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Yang R, Li HH, Van Hecke K, Cui GH. Cobalt(II) and Copper(II) Complexes Constructed from Bis(benzimidazole) and 2,6-Pyridinedicarboxylate Co-ligands: Synthesis, Crystal Structures, and Catalytic Properties. Z Anorg Allg Chem 2015. [DOI: 10.1002/zaac.201400464] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Yang R, Van Hecke K, Yu BY, Li GY, Cui GH. Cobalt(II) and silver(I) coordination polymers constructed from flexible bis(5,6-dimethylbenzimidazole) and substituted isophthalate co-ligands. TRANSIT METAL CHEM 2014. [DOI: 10.1007/s11243-014-9829-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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