Zeitschriftenartikel: „Catalysis“

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Zhao, Xiaodan, und Lihao Liao. „Modern Organoselenium Catalysis: Opportunities and Challenges“. Synlett 32, Nr. 13 (11.05.2021): 1262–68. http://dx.doi.org/10.1055/a-1506-5532.

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AbstractOrganoselenium catalysis has attracted increasing interest in recent years. This Cluster highlights recent key advances in this area regarding the functionalization of alkenes, alkynes, and arenes by electrophilic selenium catalysis, selenonium salt catalysis, selenium-based chalcogen-bonding catalysis, and Lewis basic selenium catalysis. These achievements might inspire and help future research.1 Introduction2 Electrophilic Selenium Catalysis3 Selenonium Salt Catalysis4 Selenium-Based Chalcogen-Bond Catalysis5 Lewis Basic Selenide Catalysis6 Conclusion

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Zhou, Wen-Jun, Da-Gang Yu, Yi-Han Zhang, Yong-Yuan Gui und Liang Sun. „Merging Transition-Metal Catalysis with Photoredox Catalysis: An Environmentally Friendly Strategy for C–H Functionalization“. Synthesis 50, Nr. 17 (08.08.2018): 3359–78. http://dx.doi.org/10.1055/s-0037-1610222.

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Transition-metal-catalyzed C–H functionalization is already a useful tool in organic synthesis, whilst the rapid development of photoredox catalysis provides new pathways for C–H functionalization with high selectivity and efficiency under mild reaction conditions. In this review, recent advances in C–H functionalization through merging transition-metal catalysis with photoredox catalysis are discussed.1 Introduction2 Merging Nickel Catalysis with Photoredox Catalysis3 Merging Palladium Catalysis with Photoredox Catalysis4 Merging Cobalt Catalysis with Photoredox Catalysis5 Merging Photoredox Catalysis with Other Transition-Metal Catalysis6 Conclusions

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Dagorne, Samuel. „Recent Developments on N-Heterocyclic Carbene Supported Zinc Complexes: Synthesis and Use in Catalysis“. Synthesis 50, Nr. 18 (28.06.2018): 3662–70. http://dx.doi.org/10.1055/s-0037-1610088.

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The present contribution reviews the synthesis, reactivity, and use in catalysis of NHC–Zn complexes reported since 2013. NHC-stabilized Zn(II) species typically display enhanced stability relative to common organozinc species (such as Zn dialkyls), a feature of interest for the mediation of various chemical processes and the stabilization of reactive Zn-based species. Their use in catalysis is essentially dominated by reduction reactions of various unsaturated small molecules (including CO2), thus primarily involving Zn–H and Zn–alkyl derivatives as catalysts. Simple NHC adducts of Zn(II) dihalides also appear as effective catalysts for the reduction amination of CO2 and borylation of alkyl/aryl halides. Stable and well-defined Zn alkoxides have also been prepared and behave as effective catalysts in the polymerization of cyclic esters/carbonates for the production of well-defined biodegradable materials. Overall, the attractive features of NHC-based Zn(II) species include ready access, a reasonable stability/reactivity balance, and steric/electronic tunability (through the NHC source), which should promote their further development.1 Introduction2 NHC-Supported Zinc Alkyl/Aryl Species2.1 Synthesis2.2 Reactivity and Use in Catalysis3 NHC-Supported Zinc Hydride Species3.1 Synthesis3.2 Reactivity and Use in Catalysis4 NHC-Supported Zinc Amido/Alkoxide Species4.1 Synthesis4.2 Use in Catalysis5 NHC-Supported Zinc Dihalide Species5.1 Synthesis5.2 Use in Catalysis6 Other NHC-Stabilized Zn Species7 Conclusion

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Fañanás-Mastral, Martín, Eva Rivera-Chao und Laura Fra. „Synergistic Bimetallic Catalysis for Carboboration of Unsaturated Hydrocarbons“. Synthesis 50, Nr. 19 (09.07.2018): 3825–32. http://dx.doi.org/10.1055/s-0037-1610434.

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Synergistic bimetallic catalysis has become a very efficient tool for the selective carboboration of unsaturated hydrocarbons. This synthetic approach is based on the use of a catalytically generated boron-substituted organocopper nucleophile in a cross-coupling reaction catalyzed by a second transition metal. This way, hydrocarbons can be used as pro-nucleophiles in this type of transformations thus rendering a clean and operationally simple alternative to the traditional cross-coupling methodologies. This review provides a summary of the developments on this topic and discusses both the synthetic utility and mechanisms of these reactions.1 Introduction2 Carboboration of Alkenes via Synergistic Catalysis3 Carboboration of 1,3-Dienes via Synergistic Catalysis4 Carboboration of Alkynes via Synergistic Catalysis5 Conclusions

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Ding, Bo, Qilin Xue, Hong-Gang Cheng, Qianghui Zhou und Shihu Jia. „Recent Advances in Catalytic Nonenzymatic Kinetic Resolution of Tertiary Alcohols“. Synthesis 54, Nr. 07 (02.12.2021): 1721–32. http://dx.doi.org/10.1055/a-1712-0912.

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AbstractThe kinetic resolution (KR) of racemates is one of the most widely used approaches to access enantiomerically pure compounds. Over the past two decades, catalytic nonenzymatic KR has gained popularity in the field of asymmetric synthesis due to the rapid development of chiral catalysts and ligands in asymmetric catalysis. Chiral tertiary alcohols are prevalent in a variety of natural products, pharmaceuticals, and biologically active chiral compounds. The catalytic nonenzymatic KR of racemic tertiary alcohols is a straightforward strategy to access enantioenriched tertiary alcohols. This short review describes recent advances in catalytic nonenzymatic KR of tertiary alcohols, including organocatalysis and metal catalysis.1 Introduction2 Organocatalysis2.1 Peptide Catalyst2.2 Chiral Phosphoric Acid Catalyst2.3 Chiral Lewis Base Catalyst2.4 Chiral Quaternary Ammonium Salt Catalyst3 Metal Catalysis3.1 Mixed La-Li Heterobimetallic Catalyst3.2 Rh Catalyst3.3 Hf Catalyst3.4 Pd Catalyst3.5 Cu Catalyst3.6 Ag Catalyst4 Conclusion and Outlook

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Kaplunenko, Volodymyr, und Mykola Kosinov. „Electric field - induced catalysis. Laws of field catalysis“. InterConf, Nr. 26(129) (18.10.2022): 332–51. http://dx.doi.org/10.51582/interconf.19-20.10.2022.037.

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Abstract.The article explores a new type of catalysis - electric field catalysis. The laws of field catalysis are given. The characteristics of the electric field are determined, which set the values of the characteristics of the field catalysis. Field catalysis and field catalyst do not fit into the traditional definition of catalysis and catalyst, which may require a revision of the terminology of catalysis. The field is a more versatile catalyst compared to material catalysts, both in terms of its application to a wider range of chemical reactions, and in the ability to control the rate and selectivity. It is shown that a common donor-acceptor mechanism of catalysis is realized in heterogeneous and field catalysis. Generalized formulas are obtained, from which, as partial results, the laws of heterogeneous and field catalysis follow. New definitions of catalyst and field catalysis are given. The class of material catalysts has been expanded and supplemented with field catalysts.

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Khan, Mohammad Niyaz, und Ibrahim Isah Fagge. „Kinetics and Mechanism of Cationic Micelle/Flexible Nanoparticle Catalysis: A Review“. Progress in Reaction Kinetics and Mechanism 43, Nr. 1 (März 2018): 1–20. http://dx.doi.org/10.3184/146867818x15066862094905.

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The aqueous surfactant (Surf) solution at [Surf] > cmc (critical micelle concentration) contains flexible micelles/nanoparticles. These particles form a pseudophase of different shapes and sizes where the medium polarity decreases as the distance increases from the exterior region of the interface of the Surf/H2O particle towards its furthest interior region. Flexible nanoparticles (FNs) catalyse a variety of chemical and biochemical reactions. FN catalysis involves both positive catalysis ( i.e. rate increase) and negative catalysis ( i.e. rate decrease). This article describes the mechanistic details of these catalyses at the molecular level, which reveals the molecular origin of these catalyses. Effects of inert counterionic salts (MX) on the rates of bimolecular reactions (with one of the reactants as reactive counterion) in the presence of ionic FNs/micelles may result in either positive or negative catalysis. The kinetics of cationic FN (Surf/MX/H2O)-catalysed bimolecular reactions (with nonionic and anionic reactants) provide kinetic parameters which can be used to determine an ion exchange constant or the ratio of the binding constants of counterions.

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Williams, Ian H. „Catalysis: transition-state molecular recognition?“ Beilstein Journal of Organic Chemistry 6 (03.11.2010): 1026–34. http://dx.doi.org/10.3762/bjoc.6.117.

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The key to understanding the fundamental processes of catalysis is the transition state (TS): indeed, catalysis is a transition-state molecular recognition event. Practical objectives, such as the design of TS analogues as potential drugs, or the design of synthetic catalysts (including catalytic antibodies), require prior knowledge of the TS structure to be mimicked. Examples, both old and new, of computational modelling studies are discussed, which illustrate this fundamental concept. It is shown that reactant binding is intrinsically inhibitory, and that attempts to design catalysts that focus simply upon attractive interactions in a binding site may fail. Free-energy changes along the reaction coordinate for SN2 methyl transfer catalysed by the enzyme catechol-O-methyl transferase are described and compared with those for a model reaction in water, as computed by hybrid quantum-mechanical/molecular-mechanical molecular dynamics simulations. The case is discussed of molecular recognition in a xylanase enzyme that stabilises its sugar substrate in a (normally unfavourable) boat conformation and in which a single-atom mutation affects the free-energy of activation dramatically.

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Shubina, Tatyana E., und Timothy Clark. „Catalysis of the Quadricyclane to Norbornadiene Rearrangement by SnCl2 and CuSO4“. Zeitschrift für Naturforschung B 65, Nr. 3 (01.03.2010): 347—r369. http://dx.doi.org/10.1515/znb-2010-0319.

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Ab initio and density-functional theory (DFT) calculations have been used to investigate the model rearrangements of quadricyclane to norbornadiene catalysed by single CuSO4 and SnCl2 molecules. The isolated reactions with the two molecular catalysts proceed via electron-transfer catalysis in which the hydrocarbon is oxidised, in contrast to systems investigated previously in which the substrate was reduced. The even-electron SnCl2-catalysed reaction shows singlet-triplet two-state reactivity. Solvation by a single methanol molecule changes the mechanism of the rearrangement to a classical Lewis acid-base process.

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Hidayati, Nur, Rahmah Puspita Sari und Herry Purnama. „Catalysis of glycerol acetylation on solid acid catalyst: a review“. Jurnal Kimia Sains dan Aplikasi 23, Nr. 12 (14.01.2021): 414–23. http://dx.doi.org/10.14710/jksa.23.12.414-423.

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Biodiesel is a substitute fuel that is environmentally friendly, biodegradable, and sustainable. The need for biodiesel continues to increase. Biodiesel is made through the process of transesterification of triglycerides and alcohol. Glycerol is a side-effect of biodiesel products with a capacity of 10% of the total weight of its production. Glycerol is the simplest glyceride compound and has several functions as a primary ingredient in chemical production. Through acetylation, glycerol is converted to a material that has a higher sale value. Both homogeneous and heterogeneous catalysts are the acetylation approach to achieve the desired product, namely acetyl glycerol esters (mono-, di- and triacetin). However, in the process, the catalyst’s type and characteristics significantly affect the yield and conversion of the product and the deactivation or reusability of the catalyst, which can inhibit the catalyst’s utilization and effectiveness; therefore, it must be studied further. Besides, the parameters that affect the reaction will also be assessed.

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Baráth, Eszter. „Selective Reduction of Carbonyl Compounds via (Asymmetric) Transfer Hydrogenation on Heterogeneous Catalysts“. Synthesis 52, Nr. 04 (02.01.2020): 504–20. http://dx.doi.org/10.1055/s-0039-1691542.

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Based on the ever-increasing demand for optically pure compounds, the development of efficient methods to produce such products is very important. Homogeneous asymmetric catalysis occupies a prominent position in the ranking of chemical transformations, with transition metals coordinated to chiral ligands being applied extensively for this purpose. However, heterogeneous catalysts have the ability to further extend the field of asymmetric transformations, because of their beneficial properties such as high stability, ease of separation and regeneration, and the possibility to apply them in continuous processes. The main challenge is to find potential synthetic routes that can provide a chemically and thermally stable heterogeneous catalyst having the necessary chiral information, whilst keeping the catalytic activity and enantioselectivity equally high (or even higher) than the corresponding homogeneous counterpart. Within this short review, the most relevant immobilization modes and preparative strategies depending on the support material used are summarized. From the reaction scope viewpoint, metal catalysts supported on the various solid materials studied in (asymmetric) transfer hydrogenation of carbonyl compounds are selected and represent the main focus of the second part of this overview.1 Introduction2 Synthesis of Chiral Heterogeneous Catalysts2.1 Immobilization of Homogeneous Asymmetric Catalysts2.1.1 Immobilization on Inorganic Supports2.1.2 Immobilization on Organic Polymers as Supports2.1.3 Immobilization on Dendrimer-Type Materials as Supports2.1.4 Self-Supported Chiral Catalysts: Coordination Polymers2.1.5 Immobilization Using Non-Conventional Media2.2 Chirally Modified Metal Surfaces for Heterogeneous Asymmetric Catalysis3 Examples of Transfer Hydrogenation on Heterogeneous Catalysts3.1 Silicon-Immobilized Catalysts3.2 Carbon-Material-Immobilized Catalysts3.3 Polymer-Immobilized Catalysts3.4 Magnetic-Nanoparticle-Immobilized Catalysts4 Conclusions

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Lilley, David M. J. „RNA catalysis: More than a messenger“. Biochemist 28, Nr. 2 (01.04.2006): 7–10. http://dx.doi.org/10.1042/bio02802007.

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Among the many roles that RNA has in the cell, one of the most surprising is that of an enzyme -- surprising because it has very sparse resources for this role. Yet some extremely important cellular reactions are catalysed by ribozymes, and such species may have played a key role in the evolution of life on the planet. Explaining the mechanistic origins of catalysis has been a challenge to the RNA chemist, but significant progress has been made in recent times. Ribozymes seem to use similar approaches to function as catalysts, but achieve them in different ways.

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Taqui Khan, M. M. „Carbonylation Reactions in Aqueous or Mixed Solvent Systems“. Platinum Metals Review 35, Nr. 2 (01.04.1991): 70–82. http://dx.doi.org/10.1595/003214091x3527082.

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In recent years much interest has been focused on carbonylation reactions in aqueous or biphasic systems catalysed by platinum group metals complexes. This is due to the reactivity of platinum group metals ions as catalysts designed to activate small molecules. When used in C, chemistry a variety of reactions can be catalysed by these complexes, in particular by ruthenium complexes. Ruthenium has several oxidation states and co-ordination numbers, and is relatively cheap. Additionally, ruthenium catalysts are stable and their reaction conditions are usually mild, making them excellent for homogeneous catalysis. Various reactions of ruthenium carbonyl complexes and ruthenium saloph dichloride complexes with carbon monoxide have been investigated in this laboratory, and are considered here.

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Ye, Rong, Tyler J. Hurlburt, Kairat Sabyrov, Selim Alayoglu und Gabor A. Somorjai. „Molecular catalysis science: Perspective on unifying the fields of catalysis“. Proceedings of the National Academy of Sciences 113, Nr. 19 (25.04.2016): 5159–66. http://dx.doi.org/10.1073/pnas.1601766113.

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Colloidal chemistry is used to control the size, shape, morphology, and composition of metal nanoparticles. Model catalysts as such are applied to catalytic transformations in the three types of catalysts: heterogeneous, homogeneous, and enzymatic. Real-time dynamics of oxidation state, coordination, and bonding of nanoparticle catalysts are put under the microscope using surface techniques such as sum-frequency generation vibrational spectroscopy and ambient pressure X-ray photoelectron spectroscopy under catalytically relevant conditions. It was demonstrated that catalytic behavior and trends are strongly tied to oxidation state, the coordination number and crystallographic orientation of metal sites, and bonding and orientation of surface adsorbates. It was also found that catalytic performance can be tuned by carefully designing and fabricating catalysts from the bottom up. Homogeneous and heterogeneous catalysts, and likely enzymes, behave similarly at the molecular level. Unifying the fields of catalysis is the key to achieving the goal of 100% selectivity in catalysis.

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Habib, Umair, Farooq Ahmad, Muhammad Awais, Namisa Naz, Maira Aslam, Malka Urooj, Anam Moqeem et al. „Sustainable Catalysis: Navigating Challenges and Embracing Opportunities for a Greener Future“. Journal of Chemistry and Environment 2, Nr. 2 (04.10.2023): 14–53. http://dx.doi.org/10.56946/jce.v2i2.205.

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Catalysis plays a crucial role in sustainable chemistry, as demonstrated in this review article. The introduction highlights the importance of catalysis in sustainability and summarizes catalysis research. In this review, we discussed sustainable catalysis, including green chemistry, sustainable catalysis criteria, and catalytic reactions. These examples demonstrate CO2 conversion, alcohol dehydrogenation, alkene oxidation, and biomass-to-biofuel conversion using zeolites. This study also examines sustainable catalysis difficulties like stability, synthesis, design, recovery, reuse, scale-up, and commercialization. Sustainable catalysis can be achieved via bio-inspired catalysts, renewable energy sources, nano-catalysis methods, computational methods, and innovative catalysts developed for sustainable chemistry. This study also includes sustainable catalysis case studies for CO2, biomass, water treatment, and renewable energy conversion. The review finishes with sustainable catalysis research directions. These directions include studying metal-free catalysis, integrating catalysis with other sustainable fuel cell technologies, implementing sustainable catalysis in industry, and its environmental and societal impacts. The topic covers photocatalysis, heterogeneous catalysis, and electrocatalysis, highlighting their environmental and economic effects. This comprehensive study of sustainable catalysis shows its potential to transform chemical reactions while emphasizing environmental and social concerns, improving green chemistry.

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Kim, Byungjun, Yongjae Kim und Sarah Yunmi Lee. „Stereoselective Michael Additions of Arylacetic Acid Derivatives by Asymmetric Organocatalysis“. Synlett 33, Nr. 07 (05.01.2022): 609–16. http://dx.doi.org/10.1055/s-0041-1737323.

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AbstractBecause of the versatility of chiral 1,5-dicarbonyl structural motifs, the development of stereoselective Michael additions of arylacetic acid derivatives to electron-deficient alkenes is an important challenge. Over recent decades, an array of enantio- and diastereoselective methods of this type have been developed through the use of chiral organocatalysts. In this article, three distinct strategies in this research area are highlighted. Catalytic generation of either a chiral iminium electrophile (iminium catalysis) or a chiral enolate nucleophile (Lewis base catalysis) has allowed the efficient construction of stereogenic C–C bonds. We also introduce a synergistic catalytic approach involving the merger of these two catalytic cycles that provides selective access to all four stereoisomers of products with vicinal stereocenters.1 Introduction2 Iminium Catalysis3 Lewis Base Catalysis4 Synergistic Organocatalysis5 Summary

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Motokura, Ken, und Kyogo Maeda. „Recent Advances in Heterogeneous Ir Complex Catalysts for Aromatic C–H Borylation“. Synthesis 53, Nr. 18 (09.04.2021): 3227–34. http://dx.doi.org/10.1055/a-1478-6118.

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AbstractAromatic C–H borylation catalyzed by an Ir complex is among the most powerful methods for activating inert bonds. The products, i.e., arylboronic acids and their esters, are usable chemicals for the Suzuki–Miyaura cross-coupling reaction, and significant effort has been directed toward the development of homogeneous catalysis chemistry. In this short review, we present a recent overview of current heterogeneous Ir-complex catalyst developments for aromatic C–H borylation. Not only have Ir complexes been immobilized on support surfaces with phosphine and bipyridine ligands, but Ir complexes incorporated within solid materials have also been developed as highly active and reusable heterogeneous Ir catalysts. Their catalytic activities and stabilities strongly depend on their surface structures, including linker length and ligand structure.1 Introduction and Homogeneous Ir Catalysis2 Heterogeneous Ir Complex Catalysts for C–H Borylation Reactions3 Other Heterogeneous Metal Complex Catalysts for C–H Borylation Reactions4 Summary and Outlook

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Iglesias, Daniel, und Michele Melchionna. „Enter the Tubes: Carbon Nanotube Endohedral Catalysis“. Catalysts 9, Nr. 2 (01.02.2019): 128. http://dx.doi.org/10.3390/catal9020128.

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The unique morphological characteristics of carbon nanotubes (CNTs) present the intriguing opportunity of exploiting the inner cavity for carrying out chemical reactions. Such reactions are catalysed either by the individual tubes that function both as catalysts and nanoreactors or by additional catalytic species that are confined within the channel. Such confinement creates what is called “confinement effect”, which can result in different catalytic features affecting activity, stability and selectivity. The review highlights the recent major advancements of catalysis conducted within the CNTs, starting from the synthesis of the catalytic composite, and discussing the most notable catalytic processes that have been reported in the last decade.

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Wan, Qiang, Sen Lin und Hua Guo. „Frustrated Lewis Pairs in Heterogeneous Catalysis: Theoretical Insights“. Molecules 27, Nr. 12 (10.06.2022): 3734. http://dx.doi.org/10.3390/molecules27123734.

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Frustrated Lewis pair (FLP) catalysts have attracted much recent interest because of their exceptional ability to activate small molecules in homogeneous catalysis. In the past ten years, this unique catalysis concept has been extended to heterogeneous catalysis, with much success. Herein, we review the recent theoretical advances in understanding FLP-based heterogeneous catalysis in several applications, including metal oxides, functionalized surfaces, and two-dimensional materials. A better understanding of the details of the catalytic mechanism can help in the experimental design of novel heterogeneous FLP catalysts.

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Lomic, Gizela, Erne Kis, Goran Boskovic und Radmila Marinkovic-Neducin. „Application of scanning electron microscopy in catalysis“. Acta Periodica Technologica, Nr. 35 (2004): 67–77. http://dx.doi.org/10.2298/apt0435067l.

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A short survey of various information obtained by scanning electron microscopy (SEM) in the investigation of heterogeneous catalysts and nano-structured materials have been presented. The capabilities of SEM analysis and its application in testing catalysts in different fields of heterogeneous catalysis are illustrated. The results encompass the proper way of catalyst preparation, the mechanism of catalyst active sites formation catalysts changes and catalyst degradation during their application in different chemical processes. Presented SEM pictures have been taken on a SEM JOEL ISM 35 over 25 years of studies in the field of heterogeneous catalysis.

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Crawford, Jennifer, und Matthew Sigman. „Conformational Dynamics in Asymmetric Catalysis: Is Catalyst Flexibility a Design Element?“ Synthesis 51, Nr. 05 (08.01.2019): 1021–36. http://dx.doi.org/10.1055/s-0037-1611636.

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Traditionally, highly selective low molecular weight catalysts have been designed to contain rigidifying structural elements. As a result, many proposed stereochemical models rely on steric repulsion for explaining the observed selectivity. Recently, as is the case for enzymatic systems, it has become apparent that some flexibility can be beneficial for imparting selectivity. Dynamic catalysts can reorganize to maximize attractive non-covalent interactions that stabilize the favored diastereomeric transition state, while minimizing repulsive non-covalent interactions for enhanced selectivity. This short review discusses catalyst conformational dynamics and how these effects have proven beneficial for a variety of catalyst classes, including tropos ligands, cinchona alkaloids, hydrogen-bond donating catalysts, and peptides.1 Introduction2 Tropos Ligands3 Cinchona Alkaloids4 Hydrogen-Bond Donating Catalysts5 Peptide Catalysts6 Conclusion

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Ponce, Adrian. „Radionuclide-induced defect sites in iron-bearing minerals may have accelerated the emergence of life“. Interface Focus 9, Nr. 6 (18.10.2019): 20190085. http://dx.doi.org/10.1098/rsfs.2019.0085.

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The emergence of life on Earth (and elsewhere) must have occurred in a milieu that is far from equilibrium, such as at alkaline hydrothermal vents that would have harboured built-in gradients in temperature, redox potential and pH along with precipitated iron-bearing minerals capable of separating these gradients, concentrating reactants and catalysing requisite protobiotic reactions. Iron-bearing minerals such as mackinawite, greenalite and fougèrite have been investigated as catalysts for protobiotic reactions, including amino acid synthesis. In the field of heterogeneous catalysis, it is well known that defect sites in the crystal structure are often the most active sites for catalysis, and mineral catalysts that have been exposed to ionizing radiation are known to exhibit increased reactivity due to radiation-induced defect sites. In this work, we (i) review the literature on the radioactive environment of the Hadean era, (ii) highlight the role of radionuclide ionizing radiation from 238 U, 232 Th and 40 K in generating defect sites with high catalytic activity for the chemical evolution of organic molecules, and (iii) hypothesize that these processes accelerated the emergence of life.

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Li, Shangkun, Rizwan Ahmed, Yanhui Yi und Annemie Bogaerts. „Methane to Methanol through Heterogeneous Catalysis and Plasma Catalysis“. Catalysts 11, Nr. 5 (01.05.2021): 590. http://dx.doi.org/10.3390/catal11050590.

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Direct oxidation of methane to methanol (DOMTM) is attractive for the increasing industrial demand of feedstock. In this review, the latest advances in heterogeneous catalysis and plasma catalysis for DOMTM are summarized, with the aim to pinpoint the differences between both, and to provide some insights into their reaction mechanisms, as well as the implications for future development of highly selective catalysts for DOMTM.

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Yap, Daryl Q. J., Raju Cheerlavancha, Renecia Lowe, Siyao Wang und Luke Hunter. „Investigation of cis- and trans-4-Fluoroprolines as Enantioselective Catalysts in a Variety of Organic Transformations“. Australian Journal of Chemistry 68, Nr. 1 (2015): 44. http://dx.doi.org/10.1071/ch14129.

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Stereoselective fluorination is known to rigidify the ring structure of l-proline, as a result of a combination of electrostatic and hyperconjugative effects associated with the C–F bond. This is a potential strategy for enhancing the enantioselectivity of proline-catalysed reactions. In this study, cis- and trans-4-fluoroprolines were investigated as catalysts in five different organic transformations, including examples of both enamine and iminium ion catalysis. Some significant differences in enantioselectivity were observed between the cis- and trans-isomers of the fluorinated catalysts, confirming that the ring pucker is important. However, no substantial improvements were observed relative to the parent catalyst, l-proline.

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Abu-Reziq, Raed, und Howard Alper. „Magnetically Separable Base Catalysts: Heterogeneous Catalysis vs. Quasi-Homogeneous Catalysis“. Applied Sciences 2, Nr. 2 (26.03.2012): 260–76. http://dx.doi.org/10.3390/app2020260.

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Ross, Julian. „API Abstracts - Catalysts and Catalysis“. Applied Catalysis 30, Nr. 1 (März 1987): 192. http://dx.doi.org/10.1016/s0166-9834(00)81032-5.

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Catlow, Richard. „Modelling of catalysts and catalysis“. Journal of Computer-Aided Materials Design 3, Nr. 1-3 (August 1996): 56–60. http://dx.doi.org/10.1007/bf01185636.

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Degnan, Tom. „Green catalysts and green catalysis“. Focus on Catalysts 2024, Nr. 9 (September 2024): 1. http://dx.doi.org/10.1016/j.focat.2024.09.001.

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Wu, Zhiyi, Jiahui Shen, Chaoran Li, Chengcheng Zhang, Chunpeng Wu, Zimu Li, Xingda An und Le He. „Niche Applications of MXene Materials in Photothermal Catalysis“. Chemistry 5, Nr. 1 (06.03.2023): 492–510. http://dx.doi.org/10.3390/chemistry5010036.

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MXene materials have found emerging applications as catalysts for chemical reactions due to their intriguing physical and chemical applications. In particular, their broad light response and strong photothermal conversion capabilities are likely to render MXenes promising candidates for photothermal catalysis, which is drawing increasing attention in both academic research and industrial applications. MXenes are likely to satisfy all three criteria of a desirable photothermal catalyst: strong light absorption, effective heat management, and versatile surface reactivity. However, their specific functionalities are largely dependent on their structure and composition, which makes understandings of the structure–function relationship of crucial significance. In this review, we mainly focus on the recent progress of MXene–based photothermal catalysts, emphasizing the functionalities and potential applications of MXene materials in fields of photothermal catalysis, and provide insights on design principles of highly efficient MXene–based photothermal catalysts from the atomic scale. This review provides a relatively thorough understanding of MXene–based materials for photothermal catalysis, as well as an in–depth investigation of emerging high-prospect applications in photothermal catalysis.

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Saha, Debasree, und Chhanda Mukhopadhyay. „Metal Nanoparticles: An Efficient Tool for Heterocycles Synthesis and Their Functionalization via C-H Activation“. Current Organocatalysis 6, Nr. 2 (24.06.2019): 79–91. http://dx.doi.org/10.2174/2213337206666181226152743.

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Background: Metal nanoparticles have been extensively used in the synthesis of organic molecules during the last few decades especially due to their high catalytic activity. Organic reactions involving C-H functionalisations are very much in demand as they provide a direct method of derivatisation of organic molecules, thus making the process economical. In the recent years, metal nanoparticles catalysed C-H activation reactions have led to the design of useful molecules especially heterocyclic motifs which form the core structure of drugs and thus have high biological and industrial importance. Methods: In this review, we present a collection of reactions where metal nanoparticles are instrumental in the synthesis and functionalization of heterocycles via C-H activation. The review consists of three units namely, Nano-copper catalysed C-H activation reactions, nano-palladium catalysed CH activation reactions and other nano-metals catalysed C-H activation reactions. Results: The discussion reflects the scope of nano-metals as effective catalysts for the synthesis and functionalization of heterocycles as well as the efficiency of nano-metals towards catalysing economic and environmentally viable reaction protocols. Conclusion: The theme of this review is to correlate nanometal catalysis, heterocyclic synthesis and C-H activation, each of which in itself forms an integral part of modern day chemical research. Thus, the review will hopefully highlight the need for future development and research in this area and be instrumental in guiding researchers towards fulfilling that goal.

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Kobayashi, Shū, und Kei Manabe. „Green Lewis acid catalysis in organic synthesis“. Pure and Applied Chemistry 72, Nr. 7 (01.01.2000): 1373–80. http://dx.doi.org/10.1351/pac200072071373.

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New types of Lewis acids as water-stable catalysts have been developed. Metal salts such as rare earth metal triflates can be used in carbon_carbon bond-forming reactions in aqueous media. These salts can be recovered after the reactions and reused. Furthermore, Lewis acid_surfactant-combined catalysts, which can be used for reactions in water without using any organic solvents, have been also developed. Finally, Lewis acid catalysis in supercritical carbon dioxide has been successfully performed. These investigations will contribute to development of environmentally friendly Lewis acid catalysis.

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Nori, Valeria, Fabio Pesciaioli, Arianna Sinibaldi, Giuliana Giorgianni und Armando Carlone. „Boron-Based Lewis Acid Catalysis: Challenges and Perspectives“. Catalysts 12, Nr. 1 (22.12.2021): 5. http://dx.doi.org/10.3390/catal12010005.

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In the last two decades, boron-based catalysis has been gaining increasing traction in the field of organic synthesis. The use of halogenated triarylboranes as main group Lewis acid catalysts is an attractive strategy. It has been applied in a growing number of transformations over the years, where they may perform comparably or even better than the gold standard catalysts. This review discusses methods of borane synthesis and cutting-edge boron-based Lewis acid catalysis, focusing especially on tris(pentafluorophenyl)-borane [B(C6F5)3], and other halogenated triarylboranes, highlighting how boron Lewis acids employed as catalysts can unlock a plethora of unprecedented chemical transformations or improve the efficiency of existing reactions.

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Trunschke, Annette, Giulia Bellini, Maxime Boniface, Spencer J. Carey, Jinhu Dong, Ezgi Erdem, Lucas Foppa et al. „Towards Experimental Handbooks in Catalysis“. Topics in Catalysis 63, Nr. 19-20 (06.10.2020): 1683–99. http://dx.doi.org/10.1007/s11244-020-01380-2.

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AbstractThe “Seven Pillars” of oxidation catalysis proposed by Robert K. Grasselli represent an early example of phenomenological descriptors in the field of heterogeneous catalysis. Major advances in the theoretical description of catalytic reactions have been achieved in recent years and new catalysts are predicted today by using computational methods. To tackle the immense complexity of high-performance systems in reactions where selectivity is a major issue, analysis of scientific data by artificial intelligence and data science provides new opportunities for achieving improved understanding. Modern data analytics require data of highest quality and sufficient diversity. Existing data, however, frequently do not comply with these constraints. Therefore, new concepts of data generation and management are needed. Herein we present a basic approach in defining best practice procedures of measuring consistent data sets in heterogeneous catalysis using “handbooks”. Selective oxidation of short-chain alkanes over mixed metal oxide catalysts was selected as an example.

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Lilley, David M. J. „Mechanisms of RNA catalysis“. Philosophical Transactions of the Royal Society B: Biological Sciences 366, Nr. 1580 (27.10.2011): 2910–17. http://dx.doi.org/10.1098/rstb.2011.0132.

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Ribozymes are RNA molecules that act as chemical catalysts. In contemporary cells, most known ribozymes carry out phosphoryl transfer reactions. The nucleolytic ribozymes comprise a class of five structurally-distinct species that bring about site-specific cleavage by nucleophilic attack of the 2′-O on the adjacent 3′-P to form a cyclic 2′,3′-phosphate. In general, they will also catalyse the reverse reaction. As a class, all these ribozymes appear to use general acid–base catalysis to accelerate these reactions by about a million-fold. In the Varkud satellite ribozyme, we have shown that the cleavage reaction is catalysed by guanine and adenine nucleobases acting as general base and acid, respectively. The hairpin ribozyme most probably uses a closely similar mechanism. Guanine nucleobases appear to be a common choice of general base, but the general acid is more variable. By contrast, the larger ribozymes such as the self-splicing introns and RNase P act as metalloenzymes.

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García-Álvarez, Joaquín. „Special Issue: “Advances in Homogeneous Catalysis”“. Molecules 25, Nr. 7 (25.03.2020): 1493. http://dx.doi.org/10.3390/molecules25071493.

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The use of enzymes, organo-catalysts or transition metal catalysts, as opposed to the employment of stoichiometric quantities of other traditional promoters of different organic synthetic processes (like, inorganic/organic bases, Brønsted acids, radicals, etc.) has allowed the discovery of a great number of new synthetic protocols within the toolbox of organic chemists. Moreover, the employment of the aforementioned catalysts in organic synthesis permits: (i) the diminution of the global energy demand and production cost; (ii) the enhancement of both the chemoselectivity and stereoselectivity of the global process; and (iii) the reduction of metal-, organo- or bio-catalyst consumption, thanks to the possible recycling of the catalysts; all these being synthetic concepts closely related with the principles of so-called Green Chemistry. Thus, this Special Issue on “Advances in Homogenous Catalysis” has been aimed to showcase a series of stimulating contributions from international experts within different sub-areas of catalysis in organic synthesis (ranging from metal-, organo-, or bio-catalyzed organic reactions).

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Li, Feng, und Hao Li. „Spatial compartmentalisation effects for multifunctionality catalysis: From dual sites to cascade reactions“. Innovation & Technology Advances 2, Nr. 1 (12.03.2024): 1–13. http://dx.doi.org/10.61187/ita.v2i1.54.

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Catalysis plays a key role in the production of fuels, industrial chemicals and the chemical transformation of fine chemicals. As society faces increasing environmental pollution and energy crises, tandem catalysis has attracted increasing attention as an outstanding model due to its sustainability and environmental friendliness. Compared with traditional stepwise synthesis methods, tandem catalysis not only can couple several different reactions together, but also does not require the separation of intermediates, which provides new ideas for improving reaction activity, regulating product selectivity and developing new methods for catalysis. In order to catalyse cascade reactions efficiently, it is crucial to design suitable multifunctional catalysts, which should contain at least two active sites and achieve spatial separation. Here, we introduce the realisation and application of spatial segregation of metal, acidic and basic sites with examples to provide further insight into the indispensable role of active site compartmentalisation effects in tandem catalysis. In addition, this study highlights the challenges and issues associated with such catalysts, emphasising the importance of effective catalyst enhancement and environmentally sustainable catalytic transformations. The results of the study are intended to provide guidance for the development of rational and efficient catalysts.

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Clerici, Mario G. „Zeolites for Fine Chemical Production State of Art and Perspectives“. Eurasian Chemico-Technological Journal 3, Nr. 4 (10.07.2017): 231. http://dx.doi.org/10.18321/ectj573.

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The paper analyses the role of catalysis and that of renewable resources in the frame of a sustainable development. The possible uses of natural feedstocks for chemical production and the application of catalytic<br />methods to their transformations are reviewed, with emphasis on carbohydrates and vegetable oils and on zeolite catalysts, respectively. The problems arising from the embedment of active sites on the catalyst<br />surface are discussed, with the aid of specific examples taken from oxidation and acid catalysed reactions.

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Singh, Keisham. „Recent Advances in C–H Bond Functionalization with Ruthenium-Based Catalysts“. Catalysts 9, Nr. 2 (12.02.2019): 173. http://dx.doi.org/10.3390/catal9020173.

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The past decades have witnessed rapid development in organic synthesis via catalysis, particularly the reactions through C–H bond functionalization. Transition metals such as Pd, Rh and Ru constitute a crucial catalyst in these C–H bond functionalization reactions. This process is highly attractive not only because it saves reaction time and reduces waste,but also, more importantly, it allows the reaction to be performed in a highly region specific manner. Indeed, several organic compounds could be readily accessed via C–H bond functionalization with transition metals. In the recent past, tremendous progress has been made on C–H bond functionalization via ruthenium catalysis, including less expensive but more stable ruthenium(II) catalysts. The ruthenium-catalysed C–H bond functionalization, viz. arylation, alkenylation, annulation, oxygenation, and halogenation involving C–C, C–O, C–N, and C–X bond forming reactions, has been described and presented in numerous reviews. This review discusses the recent development of C–H bond functionalization with various ruthenium-based catalysts. The first section of the review presents arylation reactions covering arylation directed by N–Heteroaryl groups, oxidative arylation, dehydrative arylation and arylation involving decarboxylative and sp3-C–H bond functionalization. Subsequently, the ruthenium-catalysed alkenylation, alkylation, allylation including oxidative alkenylation and meta-selective C–H bond alkylation has been presented. Finally, the oxidative annulation of various arenes with alkynes involving C–H/O–H or C–H/N–H bond cleavage reactions has been discussed.

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Gai, P. L., K. Kourtakis, H. Dindi und S. Ziemecki. „Novel Xerogel Catalyst Materials for Hydrogenation Reactions and the Role of Atomic Scale Interfaces“. Microscopy and Microanalysis 5, S2 (August 1999): 704–5. http://dx.doi.org/10.1017/s1431927600016846.

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We are developing a new family of heterogeneous catalysts for hydrogenation catalysis. Catalyst synthesis is accomplished using colloidal polymerization chemistry which produce high surface area xerogel catalysts. These xerogels have been synthesized by one-step sol gel chemistry. These catalysts contain ruthenium and modifiers such as gold occluded or incorporated in a titanium oxide matrix. The materials, especially the modified systems exhibit favorable performance in microreactor evaluations for hydrogenation reactions and exhibit high activities. Nanostructural studies have revealed that the materials contain dispersed catalyst clusters which are desirable microstructures for the catalysis since the majority of the atoms are exposed to catalysis and are potentially active sites.The composition and atomic structure of the xerogel catalysts containing ruthenium and other metals have been examined using our in-house developments of environmental high resolution electron microscopy (EHREM) the atomic scale [1-3] and low voltage high resolution SEM (LVSEM)[4] methods.

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Jianchen, Wang, Kang Yong und Fangkuan Sun. „Mass production of thermally stable Pt single-atom catalysts for the catalytic oxidation of sulfur dioxide“. Catalysis Science & Technology 12, Nr. 1 (2022): 124–34. http://dx.doi.org/10.1039/d1cy01578h.

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Owing to the 100% atom utilization and the potential in bridging the gap between homogeneous catalysis and heterogeneous catalysis, single-atom catalysts (SACs) have doubtlessly obtained broad attention from both academia and industry.

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Shetty, Apoorva, Vandana Molahalli, Aman Sharma und Gurumurthy Hegde. „Biomass-Derived Carbon Materials in Heterogeneous Catalysis: A Step towards Sustainable Future“. Catalysts 13, Nr. 1 (23.12.2022): 20. http://dx.doi.org/10.3390/catal13010020.

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Biomass-derived carbons are emerging materials with a wide range of catalytic properties, such as large surface area and porosity, which make them ideal candidates to be used as heterogeneous catalysts and catalytic supports. Their unique physical and chemical properties, such as their tunable surface, chemical inertness, and hydrophobicity, along with being environmentally friendly and cost effective, give them an edge over other catalysts. The biomass-derived carbon materials are compatible with a wide range of reactions including organic transformations, electrocatalytic reactions, and photocatalytic reactions. This review discusses the uses of materials produced from biomass in the realm of heterogeneous catalysis, highlighting the different types of carbon materials derived from biomass that are potential catalysts, and the importance and unique properties of heterogeneous catalysts with different preparation methods are summarized. Furthermore, this review article presents the relevant work carried out in recent years where unique biomass-derived materials are used as heterogeneous catalysts and their contribution to the field of catalysis. The challenges and potential prospects of heterogeneous catalysis are also discussed.

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Chang Chien, Tzu-Chin, und Murielle F. Delley. „Interfacial Chemistry and Catalysis of Inorganic Materials“. CHIMIA 78, Nr. 1/2 (28.02.2024): 7–12. http://dx.doi.org/10.2533/chimia.2024.7.

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Heterogeneous catalysis is essential to most industrial chemical processes. To achieve a better sustainability of these processes we need highly efficient and highly selective catalysts that are based on earth-abundant materials rather than the more conventional noble metals. Here, we discuss the potential of inorganic materials as catalysts for chemical transformations focusing in particular on the promising transition metal phosphides and sulfides. We describe our recent and current efforts to understand the interfacial chemistry of these materials that governs catalysis, and to tune catalytic reactivity by controlled chemical modification of the material surfaces and by use of interfacial electric fields.

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Maksimchuk, Nataliya V., Olga V. Zalomaeva, Igor Y. Skobelev, Konstantin A. Kovalenko, Vladimir P. Fedin und Oxana A. Kholdeeva. „Metal–organic frameworks of the MIL-101 family as heterogeneous single-site catalysts“. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 468, Nr. 2143 (14.03.2012): 2017–34. http://dx.doi.org/10.1098/rspa.2012.0072.

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In this short review paper, we survey our recent findings in the catalytic applications of mesoporous metal–organic frameworks of the MIL-101 family (Fe- and Cr-MIL-101) and demonstrate their potential in two types of liquid-phase processes: (i) selective oxidation of hydrocarbons with green oxidants—O 2 and tert -butyl hydroperoxide—and (ii) coupling reaction of organic oxides with CO 2 . A comparison with conventional single-site catalysts is made with special attention to issues of the catalyst's resistance to metal leaching and the nature of catalysis.

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Leenders, Stefan H. A. M., Rafael Gramage-Doria, Bas de Bruin und Joost N. H. Reek. „Transition metal catalysis in confined spaces“. Chemical Society Reviews 44, Nr. 2 (2015): 433–48. http://dx.doi.org/10.1039/c4cs00192c.

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Panchishnyi, V. I., und I. Yu Vorobiev. „Role of oxidation catalysis in after-treatment of exhaust gases of diesel engines“. Trudy NAMI, Nr. 2 (12.07.2023): 18–30. http://dx.doi.org/10.51187/0135-3152-2023-2-18-30.

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Introduction (problem statement and relevance). The oxidation catalysis provides the necessary efficiency and performance of diesel filters for trapping dispersed particles and systems for selective treatment of nitrogen oxides. In addition, oxidation catalysts can be a tool for neutralizing emissions of methane and some non-regulated but very hazardous polycyclic and partially oxidized hydrocarbons. There are also poorly studied theoretical issues of oxidation catalysis associated with mutual influence of toxic components contained in exhaust gases of diesel engines.The purpose of the study is to clarify the oxidation catalysis role in the general problem of after-treatment of toxic emissions of diesel engines, development and testing of catalysts and converters for neutralization of toxic combustion products of engines powered by natural gas.Methodology and research methods. Research into the catalysts under flow conditions using modern methods of gas analysis, IR spectroscopy, engine tests of the developed catalytic converters.Scientific novelty and results. The paper shows the role of oxidation catalysis in solving the common problems of after-treatment of hazardous emissions of diesel engines including both direct after-treatment of toxic compounds and supporting functions. Catalysts of higher efficiency and a series of converters for gas engines have been developed. Innovative methods to increase the resistance of oxidation catalysts to sulfur oxides have been proposed.Practical significance. The developed catalysts and converter designs are recommended for implementation in KAMAZ-820.52-260 and Cummins 250 and 280 gas engines.

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Shen, Siqi, Yuanyuan Sun, Hao Sun, Yuepeng Pang, Shuixin Xia, Taiqiang Chen, Shiyou Zheng und Tao Yuan. „Research Progress in ZIF-8 Derived Single Atomic Catalysts for Oxygen Reduction Reaction“. Catalysts 12, Nr. 5 (07.05.2022): 525. http://dx.doi.org/10.3390/catal12050525.

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Transition metal (TM) single atomic catalysts (MSAC-N-C) derived from doped zeolite imidazolate frameworks (ZIF-8) are considered attractive oxygen reduction reaction (ORR) catalysts for fuel cells and metal-air batteries due to their advantages of high specific surface area, more active catalytic sites, adjustable pore size, and coordination topology features. This review provides an updated overview of the latest advances of MSAC-N-C catalysts derived from ZIF-8 precursors in ORR electrocatalysis. Particularly, some key challenges, including coordination environments regulation of catalysis center in MSAC-N-C, the active sites loading optimization and synergistic effects between TM nanoclusters/nanoparticles and the single atoms on MSAC-N-C catalysis activity, as well as their adaptability in various devices, are summarized for improving future development and application of MSAC-N-C catalysts. In addition, this review puts forward future research directions, making it play a better role in ORR catalysis for fuel cells and metal air batteries.

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BOUSBA, DALILA, CHAFIA SOBHI, AMNA ZOUAOUI und SOUAD BOUASLA. „Synthesis of activated carbon sand their application in the synthesis of monometallic and bimetallic supported catalysts“. Algerian Journal of Signals and Systems 5, Nr. 4 (15.12.2020): 190–96. http://dx.doi.org/10.51485/ajss.v5i4.116.

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Biomass-derived porous carbons are attractive materials for the synthesis of carbon-supported catalysts, carbonaceous catalysts are environmentally benign and could provide an important competitive advantage as compared to existing heterogeneous catalysts, however the surface properties of carbon materials and excellent physical and chemical properties are compatible with diverse catalysis reactions including organic transformations. Currently, activated carbons are one of well known carbonaceous materials for their catalytic properties and for use as support in heterogeneous catalysis. The supported catalysts have been successfully used in the chemical industries for a long time, in which carbon supported catalysts have allowed to a new chemical catalytic process, on the other hand Heterogeneous catalysis plays a key role in the manufacture of essential products in different fields. In this paper, we present a comparative study, between two main different methods for activated carbons (ACs) preparation namely, physical and chemical activations. Latter was prepared from agro-industrial biomass and used as a support to prepare monometallic (dry impregnation and excess impregnation) and bimetallic catalyst (successive impregnation and co impregnation).

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Sieber, Joshua D., und Toolika Agrawal. „Recent Developments in C–C Bond Formation Using Catalytic Reductive Coupling Strategies“. Synthesis 52, Nr. 18 (25.05.2020): 2623–38. http://dx.doi.org/10.1055/s-0040-1707128.

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Metal-catalyzed reductive coupling processes have emerged as a powerful methodology for the introduction of molecular complexity from simple starting materials. These methods allow for an orthogonal approach to that of redox-neutral strategies for the formation of C–C bonds by enabling cross-coupling of starting materials not applicable to redox-neutral chemistry. This short review summarizes the most recent developments in the area of metal-catalyzed reductive coupling utilizing catalyst turnover by a stoichiometric reductant that becomes incorporated in the final product.1 Introduction2 Ni Catalysis3 Cu Catalysis4 Ru, Rh, and Ir Catalysis4.1 Alkenes4.2 1,3-Dienes4.3 Allenes4.4 Alkynes4.5 Enynes5 Fe, Co, and Mn Catalysis6 Conclusion and Outlook

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Ollevier, Thierry. „Iron bis(oxazoline) complexes in asymmetric catalysis“. Catalysis Science & Technology 6, Nr. 1 (2016): 41–48. http://dx.doi.org/10.1039/c5cy01357g.

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Asymmetric reactions catalyzed by iron complexes have attracted considerable attention because iron is a ubiquitous, inexpensive, and environmentally benign metal. This overview charts the development and application of chiral iron bis(oxazoline) and pyridine-2,6-bis(oxazoline) catalysts through their most prominent and innovative uses in asymmetric catalysis, especially in Lewis acid and oxidation catalysis.

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Henderson, Alexander S., John F. Bower und M. Carmen Galan. „Carbohydrates as enantioinduction components in stereoselective catalysis“. Organic & Biomolecular Chemistry 14, Nr. 17 (2016): 4008–17. http://dx.doi.org/10.1039/c6ob00368k.

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