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Articoli di riviste sul tema "Modern catalysis"

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Autore: Grafiati

Pubblicato: 20 luglio 2024

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1

Zhao, Xiaodan, e Lihao Liao. "Modern Organoselenium Catalysis: Opportunities and Challenges". Synlett 32, n. 13 (11 maggio 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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Hooper, Reviewed by Mark. "Modern Palladium Catalysis". Platinum Metals Review 49, n. 2 (1 aprile 2005): 77–78. http://dx.doi.org/10.1595/147106705x46487.

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Wilkins, Lewis C., e Rebecca L. Melen. "Enantioselective Main Group Catalysis: Modern Catalysts for Organic Transformations". Coordination Chemistry Reviews 324 (ottobre 2016): 123–39. http://dx.doi.org/10.1016/j.ccr.2016.07.011.

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Strekalova, Anna A., Anastasiya A. Shesterkina e Leonid M. Kustov. "Recent progress in hydrogenation of esters on heterogeneous bimetallic catalysts". Catalysis Science & Technology 11, n. 22 (2021): 7229–38. http://dx.doi.org/10.1039/d1cy01603b.

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The development and research of highly effective heterogeneous catalysts for the hydrogenation of esters, providing high activity and selectivity of the formation of the corresponding alcohols, is an urgent task of modern heterogeneous catalysis.

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Sambiagio, Carlo, Stephen P. Marsden, A. John Blacker e Patrick C. McGowan. "Copper catalysed Ullmann type chemistry: from mechanistic aspects to modern development". Chem. Soc. Rev. 43, n. 10 (2014): 3525–50. http://dx.doi.org/10.1039/c3cs60289c.

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Copper-catalysed arylations represent valid and complementary alternatives to Pd catalysis. This review discusses the different mechanisms suggested for these reactions, and summarises some of their latest applications in synthesis.

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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, n. 19-20 (6 ottobre 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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Nachtsheim, Boris, e Peter Finkbeiner. "Iodine in Modern Oxidation Catalysis". Synthesis 45, n. 08 (21 marzo 2013): 979–99. http://dx.doi.org/10.1055/s-0032-1318330.

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8

Lapina, Olga B. "Modern ssNMR for heterogeneous catalysis". Catalysis Today 285 (maggio 2017): 179–93. http://dx.doi.org/10.1016/j.cattod.2016.11.005.

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9

Kunz, Doris. "Modern Metallocene Chemistry and Catalysis". Nachrichten aus der Chemie 52, n. 10 (ottobre 2004): 1085. http://dx.doi.org/10.1002/nadc.20040521032.

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Muldoon, Mark J. "Modern multiphase catalysis: new developments in the separation of homogeneous catalysts". Dalton Trans. 39, n. 2 (2010): 337–48. http://dx.doi.org/10.1039/b916861n.

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11

Saha, Debasree, e Chhanda Mukhopadhyay. "Metal Nanoparticles: An Efficient Tool for Heterocycles Synthesis and Their Functionalization via C-H Activation". Current Organocatalysis 6, n. 2 (24 giugno 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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12

Haynes, Anthony. "Concepts of Modern Catalysis and Kinetics". Synthesis 2005, n. 05 (22 marzo 2005): 851. http://dx.doi.org/10.1055/s-2005-866709.

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Grünert, W. "Concepts of Modern Kinetics and Catalysis". Chemie Ingenieur Technik 82, n. 12 (24 novembre 2010): 2231. http://dx.doi.org/10.1002/cite.201090115.

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Milo, Anat, Takashi Ooi e Thorsten Bach. "Modern Enantioselective Catalysis in Organic Chemistry". Journal of Organic Chemistry 88, n. 12 (16 giugno 2023): 7615–18. http://dx.doi.org/10.1021/acs.joc.3c01071.

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Panchishnyi, V. I., e I. Yu Vorobiev. "Role of oxidation catalysis in after-treatment of exhaust gases of diesel engines". Trudy NAMI, n. 2 (12 luglio 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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16

Gai, Pratibha L. "In Situ Electron Microscopy in catalysis research and related surface reactions". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 agosto 1989): 614–15. http://dx.doi.org/10.1017/s0424820100155049.

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Catalysis plays a major role in the modern oil and chemical industries. Solid state catalysts are most common, whilst the reactants are commodity gases and liquids. The performance of the catalysts depends strongly on their microstructure, chemistry and surface structures on a fine (nanometer) scale and electron microscopy (EM) plays an increasingly important role in the characterization. In-situ EM with an environmental cell permits direct observations of chemical reactions under near operating conditions and in conjunction with HREM and AEM can provide in favorable cases, significant atomic level information about the surface/microstructural changes and about possible reaction with substrates. In this paper, examples of catalyst materials in chemical technology and the nature of catalysis in alloy steels with applications in nuclear reactors are shown to elucidate this.A variety of supported metallic catalysts were examined: Ni/carbon, Cu/alumina and bimetallic Cu-Pd/C (both of interest in methanol synthesis), Cu-Ru/C (incyclohexane conversions) and Cu-Ni/alumina.

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Stenina, Irina, e Andrey Yaroslavtsev. "Modern Technologies of Hydrogen Production". Processes 11, n. 1 (26 dicembre 2022): 56. http://dx.doi.org/10.3390/pr11010056.

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Transitioning to energy-saving and renewable energy sources is impossible without accelerated development of hydrogen energy and hydrogen technologies. This review summarizes the state-of-the-art and recent advances of various hydrogen production processes, including but not limited to thermochemical and electrolytic processes. Their opportunities and limitations, operating conditions, and catalysts are discussed. Nowadays, most hydrogen is still produced by steam reforming of methane, its partial oxidation, or coal gasification. Considerable attention is also paid to natural gas pyrolysis. However, hydrogen produced using these technologies has a lot of impurities and needs additional purification. A series of technologies for hydrogen purification, including its filtration through palladium alloy membranes, and membrane catalysis, allowing hydrogen production and purification in one stage, are discussed. The main way to produce carbon-free hydrogen is water electrolysis using low-cost energy from nuclear or renewable sources. Both conventional and novel methods of hydrogen storage and transportation, which are an important part of the hydrogen economy, are reviewed. Biohydrogen production technologies are also discussed. Finally, prospects for further work in this field are provided. This review will be useful to researchers and manufacturers working in this field.

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Bulavchenko, Olga A., e Zakhar S. Vinokurov. "In Situ X-ray Diffraction as a Basic Tool to Study Oxide and Metal Oxide Catalysts". Catalysts 13, n. 11 (7 novembre 2023): 1421. http://dx.doi.org/10.3390/catal13111421.

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X-ray diffraction (XRD) is a standard technique that is widely applied in heterogeneous catalysis to determine phase composition, atomic structure, and size of crystallites. This review is focused on the application of in situ XRD for studying the catalysts during their “lifetime” (under synthesis, activation, operation, and deactivation conditions), limiting the objects of research to oxide and metal oxide catalysts. Also included is a brief overview of modern techniques and instruments and the latest works illustrating different aspects of this technique in catalyst research. The main conclusion is that the field of heterogeneous catalysis research would benefit substantially from the application of in situ XRD for the structural, phase, and morphological characterization of solid catalysts. Even more useful information can be obtained if XRD is combined with other techniques that are more sensitive at length scales different from that of XRD.

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Zhan, Ziye, Jiale Yan, Zhiyou Yu e Lei Shi. "Recent Advances in Asymmetric Catalysis Associated with B(C6F5)3". Molecules 28, n. 2 (8 gennaio 2023): 642. http://dx.doi.org/10.3390/molecules28020642.

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The prevalence and significance of asymmetric catalysis in the modern medicinal industry has been witnessed in recent years, which have already been used to manufacture the (S)-Naproxen and the (S)-Propranolol. With matched specificities such as the Lewis acidity and steric bulk, B(C6F5)3 has gained accelerating attention on its application in asymmetric catalysis of Diels–Alder cycloaddition reactions, carbonyl-ene cyclization, and other various reactions, which have been demonstrated by the elegant examples from the most recent literature. Some significant progress in the reaction of indirect activation of substrates through in situ generation of numerous supramolecular catalysts from B(C6F5)3 based on Lewis-acid-assisted Lewis acid (LLA) or Lewis acid assisted Brønsted acid (LBA) strategies or the reaction promoted by cooperative actions of chiral co-catalysts and B(C6F5)3 which played a direct role on the activation of substrates have been demonstrated in this review.

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García-Sancho, Cristina, e Rafael Luque. "Editorial Catalysts: Special Issue on Heterogeneous Catalysis for Valorization of Lignocellulosic Biomass". Catalysts 11, n. 6 (21 maggio 2021): 649. http://dx.doi.org/10.3390/catal11060649.

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Kazemi, Mosstafa, Massoud Ghobadi e Ali Mirzaie. "Cobalt ferrite nanoparticles (CoFe2O4 MNPs) as catalyst and support: magnetically recoverable nanocatalysts in organic synthesis". Nanotechnology Reviews 7, n. 1 (23 febbraio 2018): 43–68. http://dx.doi.org/10.1515/ntrev-2017-0138.

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AbstractRecovery and reusability of catalysts is an important aspect in modern catalysis research especially in organic synthesis. Compared to the conventional separation, magnetic separation has emerged as a robust, highly efficient, easy and rapid separation technique for products and catalysts. Cobalt ferrite nanoparticles are a well-known material, recognized as CoFe2O4MNPs, and can be used as both catalyst and a versatile support for functionalization of metals, organocatalysts. In recent times, catalysis research has clearly experienced a renaissance in the area of utility of cobalt ferrite (CoFe2O4MNPs) nanocatalysts based on their ability for recovery and reusability; the activity of these CoFe2O4MNPs was investigated in a category of organic reactions. In this review, the fabrication, characterization, and application of cobalt ferrite (CoFe2O4MNPs) nanocatalysts (CF-MNPs) in organic reactions have well summarized.

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22

HARUTA, Masatake. "Novel Catalysis by Gold: A Modern Alchemy". Journal of the Vacuum Society of Japan 51, n. 11 (2008): 721–26. http://dx.doi.org/10.3131/jvsj2.51.721.

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Andreev, A., e T. Halachev. "International conference on modern problems of catalysis". Applied Catalysis 34 (gennaio 1987): 374–75. http://dx.doi.org/10.1016/s0166-9834(00)82484-7.

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Ballester, Pablo, Anton Vidal-Ferran e Piet W. N. M. van Leeuwen. "ChemInform Abstract: Modern Strategies in Supramolecular Catalysis". ChemInform 43, n. 15 (15 marzo 2012): no. http://dx.doi.org/10.1002/chin.201215250.

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Finkbeiner, Peter, e Boris J. Nachtsheim. "ChemInform Abstract: Iodine in Modern Oxidation Catalysis". ChemInform 44, n. 24 (23 maggio 2013): no. http://dx.doi.org/10.1002/chin.201324212.

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Reis, Ana Rita, Nuno Viduedo, Daniel Raydan e Maria Manuel B. Marques. "Bimetallic (or Multimetallic) Synthesis of N-Heterocycles". Catalysts 13, n. 9 (2 settembre 2023): 1268. http://dx.doi.org/10.3390/catal13091268.

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Bimetallic (or multimetallic) catalysis has emerged as a powerful tool in modern chemical synthesis, offering improved reaction control and versatility. This review focuses on the recent developments in bimetallic sequential catalysis for the synthesis of nitrogen heterocycles, which are essential building blocks in pharmaceuticals and fine chemicals. The cooperative action of two (sometimes more) different metal catalysts enables intricate control over reaction pathways, enhancing the selectivity and efficiency of the synthesis of N-heterocyclic compounds. By activating less reactive substrates, this multimetal catalytic strategy opens new synthetic possibilities for challenging compounds. The use of catalytic materials in bimetallic systems reduces waste and improves atom efficiency, aligning with green chemistry principles. With a diverse range of metal combinations and reaction conditions, bimetallic catalysis provides access to a broad array of N-heterocyclic compounds with various functionalities. This paper highlights the significant progress made in the past decade in this topic, emphasizing the promising potential of bimetallic catalysis in drug discovery and the fine chemical industries.

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Kovtunov, Kirill V., Oleg G. Salnikov, Ivan V. Skovpin, Nikita V. Chukanov, Dudari B. Burueva e Igor V. Koptyug. "Catalytic hydrogenation with parahydrogen: a bridge from homogeneous to heterogeneous catalysis". Pure and Applied Chemistry 92, n. 7 (28 luglio 2020): 1029–46. http://dx.doi.org/10.1515/pac-2020-0203.

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AbstractOne of the essential themes in modern catalysis is that of bridging the gap between its homogeneous and heterogeneous counterparts to combine their individual advantages and overcome shortcomings. One more incentive can now be added to the list, namely the ability of transition metal complexes to provide strong nuclear magnetic resonance (NMR) signal enhancement upon their use in homogeneous hydrogenations of unsaturated compounds with parahydrogen in solution. The addition of both H atoms of a parahydrogen molecule to the same substrate, a prerequisite for such effects, is implemented naturally with metal complexes that operate via the formation of a dihydride intermediate, but not with most heterogeneous catalysts. Despite that, it has been demonstrated in recent years that various types of heterogeneous catalysts are able to perform the required pairwise H2 addition at least to some extent. This has opened a major gateway for developing highly sensitive and informative tools for mechanistic studies of heterogeneous hydrogenations and other processes involving H2. Besides, production of catalyst-free fluids with NMR signals enhanced by 3-4 orders of magnitude is essential for modern applications of magnetic resonance imaging (MRI), including biomedical research and practice. The ongoing efforts to design heterogeneous catalysts which can implement the homogeneous (pairwise) hydrogenation mechanism are reported.

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Petrovic, Slobodan, Milica Misic-Vukovic e Dusan Mijin. "Modern catalysis in the synthesis of some pharmaceuticals and fine chemicals". Chemical Industry 56, n. 1 (2002): 10–16. http://dx.doi.org/10.2298/hemind0201010p.

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Catalysis in the synthesis of Pharmaceuticals and line chemicals nowadays becomes more and more important. Synthesis that minimizes wastes is important from the economical aspect, as well as from the environmental aspect. "Green chemistry" or "green technology" is an effort to protect the environment by increasing the efficiency of the overall synthetic processes in the chemical industry by minimizing or eliminating wasteful by-products. Modern catalytic methods in the synthesis of some Pharmaceuticals and fine chemicals are discussed such as phase-transfer catalysis, biocatalysis asymmetric catalysis and, generally, solid-phase chemistry.

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Somorjai, G. A. "Modern concepts in surface science and heterogeneous catalysis". Journal of Physical Chemistry 94, n. 3 (8 febbraio 1990): 1013–23. http://dx.doi.org/10.1021/j100366a001.

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Xu, Bin-Bin, Yong-Lai Zhang, Shu Wei, Hong Ding e Hong-Bo Sun. "On-Chip Catalytic Microreactors for Modern Catalysis Research". ChemCatChem 5, n. 8 (15 aprile 2013): 2091–99. http://dx.doi.org/10.1002/cctc.201200863.

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Adams, Nicholas J., Joachim Bargon, John M. Brown, Edward J. Farrington, Erwan Galardon, Ralf Giernoth, Hanjo Heinrich, Benjamin D. John e Kenji Maeda. "Interplay of synthesis and mechanism in asymmetric homogeneous catalysis". Pure and Applied Chemistry 73, n. 2 (1 gennaio 2001): 343–46. http://dx.doi.org/10.1351/pac200173020343.

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Asymmetric homogeneous catalysis forms one of the main planks of modern organic synthesis. It has developed rapidly and largely through the application of novel ligands, whose design is very much based on insight and intuition. At the same time, a better understanding of catalytic reaction mechanisms can contribute to further progress, since it can identify the intimate relationship between ligand structure and successful applications. The presentation will concentrate on the author's research with complexes of the late transition metals and include the search for superior methodologies in hydroboration, as well as ventures into the chemistry of reactive intermediates. The latter will be exemplified from work with rhodium and palladium catalysts.

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Bakker, Eric, e Ernö Pretsch. "Modern Potentiometry". Angewandte Chemie International Edition 46, n. 30 (23 luglio 2007): 5660–68. http://dx.doi.org/10.1002/anie.200605068.

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MacDonald, M. Jason, e Godwin B. D’Cunha. "A modern view of phenylalanine ammonia lyase". Biochemistry and Cell Biology 85, n. 3 (giugno 2007): 273–82. http://dx.doi.org/10.1139/o07-018.

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Phenylalanine ammonia lyase (PAL; E.C.4.3.1.5), which catalyses the biotransformation of l-phenylalanine to trans-cinnamic acid and ammonia, was first described in 1961 by Koukol and Conn. Since its discovery, much knowledge has been gathered with reference to the enzyme’s catabolic role in microorganisms and its importance in the phenyl propanoid pathway of plants. The 3-dimensional structure of the enzyme has been characterized using X-ray crystallography. This has led to a greater understanding of the mechanism of PAL-catalyzed reactions, including the discovery of a recently described cofactor, 3,5-dihydro-5-methyldiene-4H-imidazol-4-one. In the past 3 decades, PAL has gained considerable significance in several clinical, industrial, and biotechnological applications. The reversal of the normal physiological reaction can be effectively employed in the production of optically pure l-phenylalanine, which is a precursor of the noncalorific sweetener aspartame (l-phenylalanyl-l-aspartyl methyl ester). The enzyme’s natural ability to break down l-phenylalanine makes PAL a reliable treatment for the genetic condition phenylketonuria. In this mini-review, we discuss prominent details relating to the physiological role of PAL, the mechanism of catalysis, methods of determination and purification, enzyme kinetics, and enzyme activity in nonaqueous media. Two topics of current study on PAL, molecular biology and crystal structure, are also discussed.

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Biz, Chiara, José Gracia e Mauro Fianchini. "Review on Magnetism in Catalysis: From Theory to PEMFC Applications of 3d Metal Pt-Based Alloys". International Journal of Molecular Sciences 23, n. 23 (25 novembre 2022): 14768. http://dx.doi.org/10.3390/ijms232314768.

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The relationship between magnetism and catalysis has been an important topic since the mid-20th century. At present time, the scientific community is well aware that a full comprehension of this relationship is required to face modern challenges, such as the need for clean energy technology. The successful use of (para-)magnetic materials has already been corroborated in catalytic processes, such as hydrogenation, Fenton reaction and ammonia synthesis. These catalysts typically contain transition metals from the first to the third row and are affected by the presence of an external magnetic field. Nowadays, it appears that the most promising approach to reach the goal of a more sustainable future is via ferromagnetic conducting catalysts containing open-shell metals (i.e., Fe, Co and Ni) with extra stabilization coming from the presence of an external magnetic field. However, understanding how intrinsic and extrinsic magnetic features are related to catalysis is still a complex task, especially when catalytic performances are improved by these magnetic phenomena. In the present review, we introduce the relationship between magnetism and catalysis and outline its importance in the production of clean energy, by describing the representative case of 3d metal Pt-based alloys, which are extensively investigated and exploited in PEM fuel cells.

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Dzieszkowski, Krzysztof, e Zbigniew Rafiński. "N-Heterocyclic Carbene Catalysis under Oxidizing Conditions". Catalysts 8, n. 11 (16 novembre 2018): 549. http://dx.doi.org/10.3390/catal8110549.

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N-heterocyclic carbene organocatalysis under oxidizing conditions provides a vast range of various synthetic procedures via diverse mechanisms. The available catalysts, bases, oxidants, and oxidizing methods afford numerous opportunities for developing this branch of organocatalysis. Furthermore, implementation of tandem reactions and cooperative catalysis in the described methodology significantly expands the possibilities of modern organic chemistry. This approach allows the synthesis of different structurally complex and often enantiomerically enriched substances, which can be interesting in terms of biological activity and natural product synthesis. Many esters, amides, thioesters, lactams, lactones, and other cyclic compounds obtained in oxidative or oxygenative reactions promoted by N-heterocyclic carbenes can be interesting precursors in advanced organic synthesis. Sophistication and broad applicability prove that the described synthetic approaches are exceptionally worthy of further development.

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Fiore, Michele, e René Buchet. "Symmetry Breaking of Phospholipids". Symmetry 12, n. 9 (10 settembre 2020): 1488. http://dx.doi.org/10.3390/sym12091488.

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Either stereo reactants or stereo catalysis from achiral or chiral molecules are a prerequisite to obtain pure enantiomeric lipid derivatives. We reviewed a few plausibly organic syntheses of phospholipids under prebiotic conditions with special attention paid to the starting materials as pro-chiral dihydroxyacetone and dihydroxyacetone phosphate (DHAP), which are the key molecules to break symmetry in phospholipids. The advantages of homochiral membranes compared to those of heterochiral membranes were analysed in terms of specific recognition, optimal functions of enzymes, membrane fluidity and topological packing. All biological membranes contain enantiomerically pure lipids in modern bacteria, eukarya and archaea. The contemporary archaea, comprising of methanogens, halobacteria and thermoacidophiles, are living under extreme conditions reminiscent of primitive environment and may indicate the origin of one ancient evolution path of lipid biosynthesis. The analysis of the known lipid metabolism reveals that all modern cells including archaea synthetize enantiomerically pure lipid precursors from prochiral DHAP. Sn-glycerol-1-phosphate dehydrogenase (G1PDH), usually found in archaea, catalyses the formation of sn-glycerol-1-phosphate (G1P), while sn-glycerol-3-phosphate dehydrogenase (G3PDH) catalyses the formation of sn-glycerol-3-phosphate (G3P) in bacteria and eukarya. The selective enzymatic activity seems to be the main strategy that evolution retained to obtain enantiomerically pure lipids. The occurrence of two genes encoding for G1PDH and G3PDH served to build up an evolutionary tree being the basis of our hypothesis article focusing on the evolution of these two genes. Gene encoding for G3PDH in eukarya may originate from G3PDH gene found in rare archaea indicating that archaea appeared earlier in the evolutionary tree than eukarya. Archaea and bacteria evolved probably separately, due to their distinct respective genes coding for G1PDH and G3PDH. We propose that prochiral DHAP is an essential molecule since it provides a convergent link between G1DPH and G3PDH. The synthesis of enantiopure phospholipids from DHAP appeared probably firstly in the presence of chemical catalysts, before being catalysed by enzymes which were the products of later Darwinian selection. The enzymes were probably selected for their efficient catalytic activities during evolution from large libraries of vesicles containing amino acids, carbohydrates, nucleic acids, lipids, and meteorite components that induced symmetry imbalance.

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Liu, Bei, Haosen Yang, Pengfei Hu, Guang-Sheng Wang, Yongqiang Guo e Hewei Zhao. "Dimension Engineering in Noble-Metal-Based Nanocatalysts". Catalysts 14, n. 1 (20 dicembre 2023): 9. http://dx.doi.org/10.3390/catal14010009.

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Abstract (sommario):

Catalysts play a pivotal role in modern industries, such as energy, pharmaceuticals, and petrochemicals, serving as cornerstone of high-tech production. Noble metals, such as gold, silver, and platinum group elements, possess the superb catalytic characteristics of high-temperature oxidation resistance, corrosion resistance, stable electrochemical performance, high catalytic activity, and so on. These characteristics offer excellent prospects for applications in catalysis. In this review, we summarize innovative approaches to regulating the size and morphology of nano-noble metal catalysts with different dimensions. We also showcase typical prominent examples of their applications in exhaust gas purification, battery manufacturing, water splitting, and selective hydrogenation. Finally, perspectives are discussed in terms of future research opportunities in the realm of noble metal nanocatalysts.

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38

Liu, Yuxi, Guofeng Zhao, Dingsheng Wang e Yadong Li. "Heterogeneous catalysis for green chemistry based on nanocrystals". National Science Review 2, n. 2 (30 aprile 2015): 150–66. http://dx.doi.org/10.1093/nsr/nwv014.

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Abstract Modern society has an ever-increasing demand for environmentally friendly catalytic processes. Catalysis research is working towards a solution through the development of effective heterogeneous catalysts for environment-related applications. Nanotechnologies have provided effective strategies for the preparation of nanocrystals (NCs) with well-defined sizes, shapes and compositions. Precise control of these NCs provides an important foundation for the studies of structure-performance relationships in catalysis, which is critical to the design of NCs with optimized catalytic performances for practical applications. We focus on recent advances in the development of bottom-up strategies to control NCs structures for some key catalytic applications, including CO oxidation, selective oxidation of alcohols, semihydrogenation of alkynes, and selective hydrogenation of unsaturated aldehydes and nitrobenzene. These key applications have been a popular research focus because of their significance in green chemistry. Herein we also discuss the scientific understandings of the active species and active structures of these systems to gain an insight for rational design of efficient catalytic systems for these catalytic reactions.

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39

Sassykova, L. R., Y. A. Aubakirov, S. Sendilvelan, Zh Kh Tashmukhambetova, N. K. Zhakirova, M. F. Faizullaeva, A. A. Batyrbayeva, R. G. Ryskaliyeva, B. B. Tyussyupova e T. S. Abildin. "Studying the Mechanisms of Nitro Compounds Reduction (A-Review)". Oriental Journal of Chemistry 35, n. 1 (21 gennaio 2019): 22–38. http://dx.doi.org/10.13005/ojc/350103.

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Abstract (sommario):

The article describes some variants of mechanisms of nitro compounds reduction, offered by authors in the scientific literature. The focus is on the description of the work of Kazakh and Russian chemists working in the field of catalysis. In most of the works, the classical scheme of the mechanism of the hydrogenation of Haber-Lukashevich nitrobenzene is confirmed and detailed by experimental methods. One of the interesting aspect of the article is description the mechanism of Ya.A. Dorfman which used the orbital theory of catalysis. The orbital approach of the Ya.A. Dorfman mechanism is constructed in the light of modern orbital representations and is valid for the hydrogenation of the nitro group on various catalysts. Among the discussed mechanisms are ideas of Haber, Debus, Jungers, V.P. Shmonina, Lukashevich, M. Geirovsky, Yu. B. Vasilyev, M.V. Klyuev, E.F. Weinstein, E. Gelder, Ya.A. Dorfman and others.

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40

Hiersemann, Martin. "Modern Aldol Reactions". Synthesis 2007, n. 3 (febbraio 2007): 483. http://dx.doi.org/10.1055/s-2007-970123.

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41

Waldvogel, Siegfried R. "Modern Reduction Methods". Synthesis 2009, n. 03 (26 gennaio 2009): 511. http://dx.doi.org/10.1055/s-0028-1083327.

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42

Gölitz, Peter. "Editorial: Modern Times". Angewandte Chemie International Edition 41, n. 1 (2 gennaio 2002): 3–4. http://dx.doi.org/10.1002/1521-3773(20020104)41:1<3::aid-anie3>3.0.co;2-6.

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43

Samantaray, Manoja K., Sandeep K. Mishra, Aya Saidi e Jean-Marie Basset. "Surface organometallic chemistry: A sustainable approach in modern catalysis". Journal of Organometallic Chemistry 945 (luglio 2021): 121864. http://dx.doi.org/10.1016/j.jorganchem.2021.121864.

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44

Willis, Michael C. "Modern applications of transition metal catalysis in heterocycle synthesis". Tetrahedron 65, n. 44 (ottobre 2009): 8907. http://dx.doi.org/10.1016/j.tet.2009.08.065.

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45

Kondratenko, Evgenii V. "Modern Heterogeneous Catalysis. An Introduction Von Rutger van Santen." Angewandte Chemie 129, n. 43 (22 settembre 2017): 13362. http://dx.doi.org/10.1002/ange.201709088.

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46

Kondratenko, Evgenii V. "Modern Heterogeneous Catalysis. An Introduction By Rutger van Santen." Angewandte Chemie International Edition 56, n. 43 (22 settembre 2017): 13182. http://dx.doi.org/10.1002/anie.201709088.

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47

Zamaraev, K. I. "Modern trends in catalysis: Via studies on molecular level towards design of novel catalysts and processes". Reaction Kinetics and Catalysis Letters 35, n. 1-2 (marzo 1987): 469–88. http://dx.doi.org/10.1007/bf02062181.

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48

Doronkin, Dmitry E., e Maria Casapu. "Present Challenges in Catalytic Emission Control for Internal Combustion Engines". Catalysts 11, n. 9 (24 agosto 2021): 1019. http://dx.doi.org/10.3390/catal11091019.

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49

Lu, Fu-Dong, Gui-Feng He, Liang-Qiu Lu e Wen-Jing Xiao. "Metallaphotoredox catalysis for multicomponent coupling reactions". Green Chemistry 23, n. 15 (2021): 5379–93. http://dx.doi.org/10.1039/d1gc00993a.

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Abstract (sommario):

The key advances in the field of metallaphotoredox-catalyzed multicomponent couplings in recent years are highlighted in this review. To better meet the needs of modern chemistry, further research outlooks were also proposed.

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50

van Slagmaat, Christian A. M. R., Khi Chhay Chou, Lukas Morick, Darya Hadavi, Burgert Blom e Stefaan M. A. De Wildeman. "Synthesis and Catalytic Application of Knölker-Type Iron Complexes with a Novel Asymmetric Cyclopentadienone Ligand Design". Catalysts 9, n. 10 (22 settembre 2019): 790. http://dx.doi.org/10.3390/catal9100790.

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Abstract (sommario):

Asymmetric catalysis is an essential tool in modern chemistry, but increasing environmental concerns demand the development of new catalysts based on cheap, abundant, and less toxic iron. As a result, Knölker-type catalysts have emerged as a promising class of iron catalysts for various chemical transformations, notably the hydrogenation of carbonyls and imines, while asymmetric versions are still under exploration to achieve optimal enantio-selectivities. In this work, we report a novel asymmetric design of a Knölker-type catalyst, in which the C2-rotational symmetric cyclopentadienone ligand possesses chiral substituents on the 2- and 5-positions near the active site. Four examples of the highly modular catalyst design were synthesized via standard organic procedures, and their structures were confirmed with NMR, IR, MS, and polarimetry analysis. Density functional theory (DFT) calculations were conducted to elucidate the spatial conformation of the catalysts, and therewith to rationalize the influence of structural alterations. Transfer- and H2-mediated hydrogenations were successfully established, leading to appreciable enantiomeric excesses (ee) values up to 70%. Amongst all reported Knölker-type catalysts, our catalyst design achieves one of the highest ee values for hydrogenation of acetophenone and related compounds.

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