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Articoli di riviste sul tema "Carbon-Hydrogen (C-H) Functionalization"

Autore: Grafiati
Pubblicato: 4 giugno 2021
Ultima modifica: 6 settembre 2023

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1

Fazekas, Timothy J., Jill W. Alty, Eliza K. Neidhart, Austin S. Miller, Frank A. Leibfarth, and Erik J. Alexanian. "Diversification of aliphatic C–H bonds in small molecules and polyolefins through radical chain transfer." Science 375, no. 6580 (2022): 545–50. http://dx.doi.org/10.1126/science.abh4308.

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Abstract (sommario):
The ability to selectively introduce diverse functionality onto hydrocarbons is of substantial value in the synthesis of both small molecules and polymers. Herein, we report an approach to aliphatic carbon–hydrogen bond diversification using radical chain transfer featuring an easily prepared O -alkenylhydroxamate reagent, which upon mild heating facilitates a range of challenging or previously undeveloped aliphatic carbon–hydrogen bond functionalizations of small molecules and polyolefins. This broad reaction platform enabled the functionalization of postconsumer polyolefins in infrastructure
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2

Topczewski, Joseph J., and Melanie S. Sanford. "Carbon–hydrogen (C–H) bond activation at PdIV: a Frontier in C–H functionalization catalysis." Chemical Science 6, no. 1 (2015): 70–76. http://dx.doi.org/10.1039/c4sc02591a.

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3

Kärkäs, Markus D. "Electrochemical strategies for C–H functionalization and C–N bond formation." Chemical Society Reviews 47, no. 15 (2018): 5786–865. http://dx.doi.org/10.1039/c7cs00619e.

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4

Oeschger, Raphael, Bo Su, Isaac Yu, et al. "Diverse functionalization of strong alkyl C–H bonds by undirected borylation." Science 368, no. 6492 (2020): 736–41. http://dx.doi.org/10.1126/science.aba6146.

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Abstract (sommario):
The selective functionalization of strong, typically inert carbon-hydrogen (C–H) bonds in organic molecules is changing synthetic chemistry. However, the undirected functionalization of primary C–H bonds without competing functionalization of secondary C–H bonds is rare. The borylation of alkyl C–H bonds has occurred previously with this selectivity, but slow rates required the substrate to be the solvent or in large excess. We report an iridium catalyst ligated by 2-methylphenanthroline with activity that enables, with the substrate as limiting reagent, undirected borylation of primary C–H bo
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5

Liao, Yang, Feng Liu, and Zhang-jie Shi. "Recent progress in the oxidative coupling of unactivated Csp3–H bonds with other C–H bonds." Chemical Communications 57, no. 98 (2021): 13288–96. http://dx.doi.org/10.1039/d1cc04802c.

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The oxidative coupling between two carbon–hydrogen (C–H) bonds offers the most straightforward pathway to construct C–C bonds from hydrocarbons without pre-functionalization, exhibiting high step- and atom-economy.
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6

Dhankhar, Jyoti, and Ilija Čorić. "Direct C–H Arylation." CHIMIA 76, no. 9 (2022): 777. http://dx.doi.org/10.2533/chimia.2022.777.

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Bonds between hydrogen and carbon atoms are the most frequent type of bonds in organic molecules. The ability to replace hydrogen atoms by making other types of bonds to carbon atoms can enable simpler access to complex organic molecules by substituting multistep synthetic sequences. The use of transition metal catalysts to activate C–H bonds is particularly attractive as it offers control over the reactivity and selectivity through catalyst design. However, such functionalization includes the difficult breaking of strong C–H bonds that are not activated by the presence of other groups. Additi
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7

Nagib, David, Leah Stateman, and Kohki Nakafuku. "Remote C–H Functionalization via Selective Hydrogen Atom Transfer." Synthesis 50, no. 08 (2018): 1569–86. http://dx.doi.org/10.1055/s-0036-1591930.

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The selective functionalization of remote C–H bonds via intramolecular hydrogen atom transfer (HAT) is transformative for organic synthesis. This radical-mediated strategy provides access to novel reactivity that is complementary to closed-shell pathways. As modern methods for mild generation of radicals are continually developed, inherent selectivity paradigms of HAT mechanisms offer unparalleled opportunities for developing new strategies for C–H functionalization. This review outlines the history, recent advances, and mechanistic underpinnings of intramolecular HAT as a guide to addressing
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8

Sarkar, Sumon, Kelvin Pak Shing Cheung, and Vladimir Gevorgyan. "C–H functionalization reactions enabled by hydrogen atom transfer to carbon-centered radicals." Chemical Science 11, no. 48 (2020): 12974–93. http://dx.doi.org/10.1039/d0sc04881j.

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9

Sarkar, Rajib, and Chhanda Mukhopadhyay. "Carbon-Hydrogen Bond Functionalization in Aqueous Medium: A Brief Review." Current Green Chemistry 6, no. 3 (2019): 184–97. http://dx.doi.org/10.2174/2213346106666191019120048.

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Abstract (sommario):
In the last few decades, considerable research has led to the introduction of selective and efficient green as well as sustainable synthetic methods of functionalization of carbon-hydrogen bonds to form new carbon-carbon and carbon-heteroatom bonds. In this emerging field, significant development has been attained under various environmentally benign conditions including aqueous medium. In this review, we have summarized the current development of C-H functionalization carried out in an aqueous medium and its synthetic applications according to carbon-carbon and carbon-heteroatom bond formatio
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10

Popov, Stasik, Brian Shao, Alex L. Bagdasarian, et al. "Teaching an old carbocation new tricks: Intermolecular C–H insertion reactions of vinyl cations." Science 361, no. 6400 (2018): 381–87. http://dx.doi.org/10.1126/science.aat5440.

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Vinyl carbocations have been the subject of extensive experimental and theoretical studies over the past five decades. Despite this long history in chemistry, the utility of vinyl cations in chemical synthesis has been limited, with most reactivity studies focusing on solvolysis reactions or intramolecular processes. Here we report synthetic and mechanistic studies of vinyl cations generated through silylium–weakly coordinating anion catalysis. We find that these reactive intermediates undergo mild intermolecular carbon-carbon bond–forming reactions, including carbon-hydrogen (C–H) insertion i
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11

Cao, Hui, Qiang Cheng, and Armido Studer. "Radical and ionic meta -C–H functionalization of pyridines, quinolines, and isoquinolines." Science 378, no. 6621 (2022): 779–85. http://dx.doi.org/10.1126/science.ade6029.

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Carbon-hydrogen (C−H) functionalization of pyridines is a powerful tool for the rapid construction and derivatization of many agrochemicals, pharmaceuticals, and materials. Because of the inherent electronic properties of pyridines, selective meta -C−H functionalization is challenging. Here, we present a protocol for highly regioselective meta -C−H trifluoromethylation, perfluoroalkylation, chlorination, bromination, iodination, nitration, sulfanylation, and selenylation of pyridines through a redox-neutral dearomatization-rearomatization process. The introduced dearomative activation mode pro
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12

Titus, E., Gil Cabral, J. C. Madaleno, et al. "Hydrogen in Chemical Vapour Deposited Carbon Nanotubes: An Active Site for Functionalization." Journal of Nanoscience and Nanotechnology 8, no. 8 (2008): 4017–22. http://dx.doi.org/10.1166/jnn.2008.an34.

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The presence of hydrogen in as-grown carbon nanotubes (CNTs) synthesized by microwave plasma (MP) chemical vapour deposition (CVD) technique is demonstrated. Our results showed that the MPCVD, as-grown CNTs were hydrogenated consisting of C—H bonds; whereas, the tubes synthesized by arc discharge consisted of non-hydrogenated multi-walled CNTs. Fourier transform infrared spectroscopy (FTIR) and micro-Raman spectroscopy techniques were used to detect C—H bonding in the as-grown CNTs. The effective functionalization of as-grown hydrogenated CNTs grown using a microwave CVD process is first time
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13

Cheng, Jian, Jin Xie, and Chengjian Zhu. "Relay photocatalytic cascade reactions: synthesis of indolo[2,1-a]isoquinoline derivatives via double C(sp3)–H bond functionalization." Chemical Communications 54, no. 13 (2018): 1655–58. http://dx.doi.org/10.1039/c7cc09820k.

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A relay photoredox catalysis strategy concomitant with [1,5] hydrogen atom transfer has been applied in the construction of a biologically important indolo[2,1-a]isoquinoline framework via a cascade reaction. This reaction enables double C(sp<sup>3</sup>)–H bond functionalization and formation of two carbon–carbon double bonds.
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14

Topczewski, Joseph J., and Melanie S. Sanford. "ChemInform Abstract: Carbon-Hydrogen (C-H) Bond Activation at PdIV: A Frontier in C-H Functionalization Catalysis." ChemInform 46, no. 12 (2015): no. http://dx.doi.org/10.1002/chin.201512322.

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15

Martínez-Laguna, Jonathan, Andrés Mollar-Cuni, David Ventura-Espinosa, et al. "Gold nanoparticle-catalysed functionalization of carbon–hydrogen bonds by carbene transfer reactions." Dalton Transactions 51, no. 13 (2022): 5250–56. http://dx.doi.org/10.1039/d1dt04351j.

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Gold nanoparticles stabilized by NHC ligands and supported onto reduced graphene oxide (rGO) catalyse the functionalization of cyclohexane and benzene C–H bonds upon insertion of carbene CHCO2Et (from N2CHCO2Et) groups.
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16

Young, Michael, Mohit Kapoor, Pratibha Chand-Thakuri, Justin Maxwell, Daniel Liu, and Hanyang Zhou. "Carbon Dioxide-Driven Palladium-Catalyzed C–H Activation of Amines: A Unified Approach for the Arylation of Aliphatic and Aromatic Primary and Secondary Amines." Synlett 30, no. 05 (2019): 519–24. http://dx.doi.org/10.1055/s-0037-1611381.

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Amines are an important class of compounds in organic chemistry and serve as an important motif in various industries, including pharmaceuticals, agrochemicals, and biotechnology. Several methods have been developed for the C–H functionalization of amines using various directing groups, but functionalization of free amines remains a challenge. Here, we discuss our recently developed carbon dioxide driven highly site-selective γ-arylation of alkyl- and benzylic amines via a palladium-catalyzed C–H bond-activation process. By using carbon dioxide as an inexpensive, sustainable, and transient dir
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17

Huo, Congde, Jie Dong, Yingpeng Su, Jing Tang, and Fengjuan Chen. "Iron-catalyzed oxidative sp3 carbon–hydrogen bond functionalization of 3,4-dihydro-1,4-benzoxazin-2-ones." Chemical Communications 52, no. 91 (2016): 13341–44. http://dx.doi.org/10.1039/c6cc05885j.

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18

Dénès, Fabrice. "Intermolecular Radical C–H Bond Activation: A Powerful Tool for Late Stage Functionalization." CHIMIA International Journal for Chemistry 74, no. 1 (2020): 23–32. http://dx.doi.org/10.2533/chimia.2020.23.

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The synthesis of complex molecules via radical reactions involving carbon–carbon and carbon–heteroatom bonds has become a very successful approach. Radical chemistry has long been dominated by the use of tin-based reagents. Those strongly contributed to the development of the field, allowing one to achieve spectacular transformations, most of which being difficult or impossible to achieve under ionic conditions, and giving access to invaluable kinetics data that paved the way for the development of improved protocols and the design of new synthetic strategies. However, tin reagents and tin byp
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19

Ali, Siraj Z., Brenna G. Budaitis, Devon F. A. Fontaine, Andria L. Pace, Jacob A. Garwin, and M. Christina White. "Allylic C–H amination cross-coupling furnishes tertiary amines by electrophilic metal catalysis." Science 376, no. 6590 (2022): 276–83. http://dx.doi.org/10.1126/science.abn8382.

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Intermolecular cross-coupling of terminal olefins with secondary amines to form complex tertiary amines—a common motif in pharmaceuticals—remains a major challenge in chemical synthesis. Basic amine nucleophiles in nondirected, electrophilic metal–catalyzed aminations tend to bind to and thereby inhibit metal catalysts. We reasoned that an autoregulatory mechanism coupling the release of amine nucleophiles with catalyst turnover could enable functionalization without inhibiting metal-mediated heterolytic carbon-hydrogen cleavage. Here, we report a palladium(II)-catalyzed allylic carbon-hydroge
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20

Ramadoss, Boobalan, Yushu Jin, Sobi Asako, and Laurean Ilies. "Remote steric control for undirected meta -selective C–H activation of arenes." Science 375, no. 6581 (2022): 658–63. http://dx.doi.org/10.1126/science.abm7599.

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Regioselective functionalization of arenes remains a challenging problem in organic synthesis. Steric interactions are often used to block sites adjacent to a given substituent, but they do not distinguish the remaining remote sites. We report a strategy based on remote steric control, whereby a roof-like ligand protects the distant para site in addition to the ortho sites, and thereby enables selective activation of meta carbon-hydrogen (C–H) bonds in the absence of ortho or para substituents. We demonstrate this concept for iridium-catalyzed meta -selective borylation of various monosubstitu
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21

Cho, Inha, Zhi-Jun Jia, and Frances H. Arnold. "Site-selective enzymatic C‒H amidation for synthesis of diverse lactams." Science 364, no. 6440 (2019): 575–78. http://dx.doi.org/10.1126/science.aaw9068.

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A major challenge in carbon‒hydrogen (C‒H) bond functionalization is to have the catalyst control precisely where a reaction takes place. In this study, we report engineered cytochrome P450 enzymes that perform unprecedented enantioselective C‒H amidation reactions and control the site selectivity to divergently construct β-, γ-, and δ-lactams, completely overruling the inherent reactivities of the C‒H bonds. The enzymes, expressed in Escherichia coli cells, accomplish this abiological carbon‒nitrogen bond formation via reactive iron-bound carbonyl nitrenes generated from nature-inspired acyl-
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22

Bellina, Fabio. "Real Metal-Free C–H Arylation of (Hetero)arenes: The Radical Way." Synthesis 53, no. 15 (2021): 2517–44. http://dx.doi.org/10.1055/a-1437-9761.

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AbstractSynthetic methodologies involving the formation of carbon–carbon bonds from carbon–hydrogen bonds are of significant synthetic interest, both for efficiency in terms of atom economy and for their undeniable usefulness in late-stage functionalization approaches. Combining these aspects with being metal-free, the radical C–H intermolecular arylation procedures covered by this review represent both powerful and green methods for the synthesis of (hetero)biaryl systems.1 Introduction2 Arylation with Arenediazonium Salts and Related Derivatives2.1 Ascorbic Acid as the Reductant2.2 Hydrazine
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23

Li, Hong-Xi, Da-Liang Zhu, and David James Young. "Carbonyl-Photoredox/Metal Dual Catalysis: Applications in Organic Synthesis." Synthesis 52, no. 23 (2020): 3493–510. http://dx.doi.org/10.1055/s-0040-1707183.

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Photoredox/metal dual catalysis is a versatile tandem methodology to construct carbon–carbon and carbon–heteroatom bonds. The focus of this short review is the application of this technology to C(sp3)–C(sp3), C(sp3)–C(sp2), C(sp2)–C(sp2), C(sp2)–O, and C(sp3)–O bond formation induced by readily available and inexpensive carbonyl complexes as single electron transfer agents, photosensitizers, or hydrogen atom transfer agents.1 Introduction2 Homocoupling of Aryl Halides3 Functionalization of C(sp3)–H Bonds3.1 Dehydrogenation of Alkanes3.2 Arylation/Alkylation3.3 Carboxylation3.4 Acylation3.5 Hyd
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24

Nistanaki, Sepand K., Chloe G. Williams, Benjamin Wigman, et al. "Catalytic asymmetric C–H insertion reactions of vinyl carbocations." Science 378, no. 6624 (2022): 1085–91. http://dx.doi.org/10.1126/science.ade5320.

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From the preparation of pharmaceuticals to enzymatic construction of natural products, carbocations are central to molecular synthesis. Although these reactive intermediates are engaged in stereoselective processes in nature, exerting enantiocontrol over carbocations with synthetic catalysts remains challenging. Many resonance-stabilized tricoordinated carbocations, such as iminium and oxocarbenium ions, have been applied in catalytic enantioselective reactions. However, their dicoordinated counterparts (aryl and vinyl carbocations) have not, despite their emerging utility in chemical synthesi
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25

Luo, Xianyou, Ping Yuan, Junhui Luo, et al. "The Enhancing Effect of Stable Oxygen Functional Groups on Porous-Carbon-Supported Pt Catalysts for Alkaline Hydrogen Evolution." Nanomaterials 13, no. 8 (2023): 1415. http://dx.doi.org/10.3390/nano13081415.

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The oxygen functionalization of carbon materials has widely been employed to improve the catalytic performance of carbon-supported Pt (Pt/C) catalysts. Hydrochloric acid (HCl) has often been employed to clean carbons during the preparation of carbon materials. However, the effect of oxygen functionalization through a HCl treatment of porous carbon (PC) supports on the performance of the alkaline hydrogen evolution reaction (HER) has rarely been investigated. Herein, the impact of HCl combined with the heat treatment of PC supports on the HER performance of Pt/C catalysts has been comprehensive
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26

D Primastari, S., Y. Kusumastuti, M. Handayani, and Rochmadi. "Functionalization of multi-walled carbon nanotube (MWCNT) with CTACe surfactant and polyethylene glycol as potential drug carrier." IOP Conference Series: Earth and Environmental Science 963, no. 1 (2022): 012033. http://dx.doi.org/10.1088/1755-1315/963/1/012033.

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Abstract Multi-walled Carbon Nanotube (MWCNT) pure is easy to form aggregate, making it difficult to apply as a drug carrier since it can be toxic to the body. It can be overcome by functionalization using surfactants, like cetyltrimethyl ammonium trichloro-monobromo-cerate (CTACe) and polyethylene glycol (PEG). First, MWCNT was functionalized with CTACe surfactant, then further PEG 6000 was used with several MWCNT-CTACe ratios. The functionalization was conducted under ultrasonic treatment, then followed by filtration, washing, and drying. The functionalized MWCNT underwent dispersion tests u
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27

Ketcham, John M., Inji Shin, T. Patrick Montgomery, and Michael J. Krische. "Catalytic Enantioselective CH Functionalization of Alcohols by Redox-Triggered Carbonyl Addition: Borrowing Hydrogen, Returning Carbon." Angewandte Chemie International Edition 53, no. 35 (2014): 9142–50. http://dx.doi.org/10.1002/anie.201403873.

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28

Engle, Keary M. "The mechanism of palladium(II)-mediated C–H cleavage with mono-N-protected amino acid (MPAA) ligands: origins of rate acceleration." Pure and Applied Chemistry 88, no. 1-2 (2016): 119–38. http://dx.doi.org/10.1515/pac-2015-0902.

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AbstractIt has long been known that transition metals are capable of interacting with, cleaving, and mediating the functionalization of activated and unactivated carbon–hydrogen (C–H) bonds. Broadly speaking, a basic underlying principle in the fields of inorganic and organometallic chemistry is that the primary and secondary coordination spheres around a metal affect its reactivity and selectivity in elementary reactions. Hence, ligand design in transition metal catalysis has been a captivating area of research for over half a century. The discovery and development of novel ligands to promote
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29

Yang, Qiaomu, Yu-Heng Wang, Yusen Qiao, et al. "Photocatalytic C–H activation and the subtle role of chlorine radical complexation in reactivity." Science 372, no. 6544 (2021): 847–52. http://dx.doi.org/10.1126/science.abd8408.

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The functionalization of methane, ethane, and other alkanes derived from fossil fuels is a central goal in the chemical enterprise. Recently, a photocatalytic system comprising [CeIVCl5(OR)]2− [CeIV, cerium(IV); OR, –OCH3 or –OCCl2CH3] was disclosed. The system was reportedly capable of alkane activation by alkoxy radicals (RO•) formed by CeIV–OR bond photolysis. In this work, we present evidence that the reported carbon-hydrogen (C–H) activation of alkanes is instead mediated by the photocatalyst [NEt4]2[CeCl6] (NEt4+, tetraethylammonium), and RO• are not intermediates. Spectroscopic analyses
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30

Ketcham, John M., Inji Shin, T. Patrick Montgomery, and Michael J. Krische. "ChemInform Abstract: Catalytic Enantioselective C-H Functionalization of Alcohols by Redox-Triggered Carbonyl Addition: Borrowing Hydrogen, Returning Carbon." ChemInform 45, no. 47 (2014): no. http://dx.doi.org/10.1002/chin.201447269.

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31

Costa, Inês, Marina Kirillova, Vânia André, Tiago Fernandes, and Alexander Kirillov. "Tetracopper(II) Cores Driven by an Unexplored Trifunctional Aminoalcohol Sulfonic Acid for Mild Catalytic C–H Functionalization of Alkanes." Catalysts 9, no. 4 (2019): 321. http://dx.doi.org/10.3390/catal9040321.

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Three new tetracopper(II) coordination compounds were easily generated from Cu(NO3)2, a trifunctional aminoalcohol sulfonic acid (H3bes, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid) as a principal building block, and a benzene carboxylic acid as a supporting ligand (i.e., benzoic (Hba), 4-hydroxybenzoic (Hfba), or 3-hydroxybenzoic (Hthba) acid). The obtained microcrystalline products, [Cu4(µ-Hbes)3(µ-H2bes)(µ-L)]·2H2O (L = ba− (1), fhba− (2), and thba− (3)), were fully characterized by FTIR (Fourier-transform infrared spectroscopy), elemental analysis, ESI-MS (Electrospray Ionisation Ma
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32

Ismagilov, Z. R., S. A. Yashnik, N. V. Shikina, et al. "Effect of Acid Treatment on the Functionalization of Surface, Structural and Textural Properties of Carbon Nanotubes Taunit." Eurasian Chemico-Technological Journal 21, no. 4 (2019): 291. http://dx.doi.org/10.18321/ectj886.

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The role of acid treatment of Taunit carbon nanotubes in the formation of oxygen-containing functional groups on its surface as well as morphological and textural properties was studied. Acid treatment was carried out in an HNO3 solution or its mixture with H2SO4 under mild conditions (85 °C/1 h) with subsequent washing with distilled water or without washing. Properties of the initial and oxidized samples were investigated using elemental carbon, hydrogen, nitrogen, oxygen (CHNO) analysis, BET (Brunauer-Emmett-Teller) determination of surface area, X-ray diffraction, Raman and Fourier Transfo
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Xia, Yuzhen, Hangwei Lei, Chuanfu Sun, et al. "Enhanced Ageing Performance of Sulfonic Acid-Grafted Pt/C Catalysts." Micromachines 13, no. 11 (2022): 1825. http://dx.doi.org/10.3390/mi13111825.

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Chemical functionalization of carbon support for Pt catalysts is a promising way to enhance the performance of catalysts. In this study, Pt/C catalysts grafted with various amounts of phenylsulfonic acid groups were prepared under mild conditions. The influence of sulfonic acid groups on the physiochemical characteristics and electrochemical activities of the modified catalysts were studied using X-ray diffraction, X-ray photoelectron spectroscopy, a transmission electron microscope, and cyclic voltammetry (CV). The presence of the chemical groups enhanced the hydrogen adsorption onto/desorpti
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34

Kirillova, Marina V., Polyana Tomé de Paiva, Wagner A. Carvalho, Dalmo Mandelli, and Alexander M. Kirillov. "Mixed-ligand aminoalcohol-dicarboxylate copper(II) coordination polymers as catalysts for the oxidative functionalization of cyclic alkanes and alkenes." Pure and Applied Chemistry 89, no. 1 (2017): 61–73. http://dx.doi.org/10.1515/pac-2016-1012.

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AbstractNew copper(II) catalytic systems for the mild oxidative C–H functionalization of cycloalkanes and cycloalkenes were developed, which are based on a series of mixed-ligand aminoalcohol-dicarboxylate coordination polymers, namely [Cu2(μ-dmea)2(μ-nda)(H2O)2]n·2nH2O (1), [Cu2(μ-Hmdea)2(μ-nda)]n·2nH2O (2), and [Cu2(μ-Hbdea)2(μ-nda)]n·2nH2O (3) that bear slightly different dicopper(II) aminoalcoholate cores, as well as on a structurally distinct dicopper(II) [Cu2(H4etda)2(μ-nda)]·nda·4H2O (4) derivative [abbreviations: H2nda, 2,6-naphthalenedicarboxylic acid; Hdmea, N,N′-dimethylethanolamine
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35

Mitsunuma, Harunobu, Xue Peng, Yuki Hirao, et al. "(Invited) Titanium-Catalyzed Intermolecular Radical Addition to Ketones Via Sp 3 C-H Bond Activation." ECS Meeting Abstracts MA2022-01, no. 13 (2022): 914. http://dx.doi.org/10.1149/ma2022-0113914mtgabs.

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Tertiary alcohols are widely present in natural products, pharmaceuticals, and agrochemicals. Radical addition reaction to ketones is a simple and waste-free synthetic method for preparation of tertiary alcohols with high functional group tolerance. Therefore, direct radical addition reactions to ketones can be applied to a wider range of substrates. However, radical addition to carbonyl groups is a thermodynamically unfavored process, especially in the case of intermolecular radical addition to ketones, where the resulting alkoxy radical can easily undergo β-fragmentation to yield the startin
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36

Fujiwara, Yuta. "My Research Activities in Baran Laboratory: Development of New Reagent/Methodology for Carbon-Hydrogen Bond Functionalization on Heteroaromatic Ring." Journal of Synthetic Organic Chemistry, Japan 71, no. 9 (2013): 953–60. http://dx.doi.org/10.5059/yukigoseikyokaishi.71.953.

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Goscianska, Joanna, Aleksander Ejsmont, Anna Olejnik, Dominika Ludowicz, Anna Stasiłowicz, and Judyta Cielecka-Piontek. "Design of Paracetamol Delivery Systems Based on Functionalized Ordered Mesoporous Carbons." Materials 13, no. 18 (2020): 4151. http://dx.doi.org/10.3390/ma13184151.

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Abstract (sommario):
The oxidized ordered mesoporous carbons of cubic and hexagonal structure obtained by two templating methods (soft and hard) were applied for the first time as delivery systems for paracetamol—the most common antipyretic and analgesic drug in the world. The process of carbon oxidation was performed using an acidic ammonium persulfate solution at 60 °C for 6 h. The functionalization was found to reduce the specific surface area and pore volume of carbon materials, but it also led to an increasing number of acidic oxygen-containing functional groups. The most important element and the novelty of
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38

Chen, Jianuo, Zunmin Guo, Ziyu Zhao, Maria Perez-Page, and Stuart Holmes. "Performance and Durability of HT-PEMFC Enhanced By One-Step Electrochemical Exfoliated Phosphonated Graphene Oxide." ECS Meeting Abstracts MA2022-01, no. 7 (2022): 628. http://dx.doi.org/10.1149/ma2022-017628mtgabs.

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The high-temperature proton exchange membrane fuel cell (HT-PEMFC) conducts protons through the hydrogen bond network established by the polymer and phosphoric acid (PA), which reduces the dependence on humidity and allows its operating temperature to be higher than 100°C [1]. A higher operating temperature is conducive to improve catalyst activity, reducing carbon dioxide adsorption on the catalyst thus reducing the requirement for hydrogen purity, and convenient water management [2]. As the most widely commercialized HT-PEMFC proton exchange membrane material, the performance and durability
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39

Laudadio, Gabriele, Yuchao Deng, Klaas van der Wal, et al. "C(sp3)–H functionalizations of light hydrocarbons using decatungstate photocatalysis in flow." Science 369, no. 6499 (2020): 92–96. http://dx.doi.org/10.1126/science.abb4688.

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Direct activation of gaseous hydrocarbons remains a major challenge for the chemistry community. Because of the intrinsic inertness of these compounds, harsh reaction conditions are typically required to enable C(sp3)–H bond cleavage, barring potential applications in synthetic organic chemistry. Here, we report a general and mild strategy to activate C(sp3)–H bonds in methane, ethane, propane, and isobutane through hydrogen atom transfer using inexpensive decatungstate as photocatalyst at room temperature. The corresponding carbon-centered radicals can be effectively trapped by a variety of M
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40

Kong, Fanji, Shusen Chen, Junqi Chen, et al. "Cu(II) carboxylate arene C─H functionalization: Tuning for nonradical pathways." Science Advances 8, no. 34 (2022). http://dx.doi.org/10.1126/sciadv.add1594.

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We report carbon-hydrogen acetoxylation of nondirected arenes benzene and toluene, as well as related functionalization with pivalate and 2-ethylhexanoate ester groups, using simple copper(II) [Cu(II)] salts with over 80% yield. By changing the ratio of benzene and Cu(II) salts, 2.4% conversion of benzene can be reached. Combined experimental and computational studies results indicate that the arene carbon-hydrogen functionalization likely occurs by a nonradical Cu(II)-mediated organometallic pathway. The Cu(II) salts used in the reaction can be isolated, recycled, and reused with little chang
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41

Guo, Li-Na, Le Liu та Xin-Hua Duan. "Recent Advance in Iminyl Radical Triggered C–H and C–C Bond Functionalization of Oxime Esters via 1,5-HAT and β-Carbon Scission". Synthesis, 7 липня 2021. http://dx.doi.org/10.1055/a-1545-6874.

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Abstract (sommario):
AbstractThe direct functionalization of C(sp3)–H and C(sp3)–C(sp3) bonds is considered as one of the most valuable synthetic strategies because of its high efficiency and step-economy for the rapid assembly of complex molecules. However, the relatively high bond disassociation energies (BDEs) and similar chemical environment lead to large obstacles in terms of low reactivity and selectivity. Using a radical-based strategy has proved to be an efficient approach to overcome these difficulties via a hydrogen atom transfer (HAT) process for selective C(sp3)–H functionalization and β-carbon scissio
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42

Leibler, Isabelle Nathalie-Marie, Makeda A. Tekle-Smith, and Abigail G. Doyle. "A general strategy for C(sp3)–H functionalization with nucleophiles using methyl radical as a hydrogen atom abstractor." Nature Communications 12, no. 1 (2021). http://dx.doi.org/10.1038/s41467-021-27165-z.

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AbstractPhotoredox catalysis has provided many approaches to C(sp3)–H functionalization that enable selective oxidation and C(sp3)–C bond formation via the intermediacy of a carbon-centered radical. While highly enabling, functionalization of the carbon-centered radical is largely mediated by electrophilic reagents. Notably, nucleophilic reagents represent an abundant and practical reagent class, motivating the interest in developing a general C(sp3)–H functionalization strategy with nucleophiles. Here we describe a strategy that transforms C(sp3)–H bonds into carbocations via sequential hydro
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43

Zhang, Yong, and Linlin Xing. "Recent Advances in Selective C-H Bonds Functionalization through Aryl RadicalMediated Hydrogen Atom Transfer Strategy." Current Organic Chemistry 25 (July 27, 2023). http://dx.doi.org/10.2174/1385272825666230727092717.

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Abstract: Selective C-H bond functionalization of organic molecules has developed as an increasingly versatile platform that found wide applications in the synthesis of naturally occurring compounds, functional group modification, material sciences, and chemical and pharmaceutical industries. Apart from transition metal catalysis, which traditionally underwent a two-electron mechanism, a recent renascence of radical chemistry based on the hydrogen atom transfer (HAT) strategy has resulted in the rapid development of C-H bond functionalization. While many methodologies involving heteroatom-base
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44

Zhao (赵维杰), Weijie. "Activate dormant C–H bonds with tons of enthusiasm: an interview with Jin-Quan Yu." National Science Review 9, no. 1 (2021). http://dx.doi.org/10.1093/nsr/nwab229.

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Abstract (sommario):
Abstract Synthetic chemistry is the art of molecules. By breaking and forming chemical bonds, chemists can transform one molecule into another, and provide a variety of chemicals that we use in our daily lives. Among all chemical bonds, the carbon-hydrogen (C–H) bond is one of the most common, and is present in almost every organic compound. Breaking C–H bonds and connecting the carbon atoms with other atoms or groups is an essential step for the synthesis of a large variety of chemicals—from bulk chemicals to functional materials and drug candidates. However, the C–H bond is extremely stable
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45

Yang, Zhaoliang, Yunhong Niu, Xiaoqian He, et al. "Tuning the reactivity of alkoxyl radicals from 1,5-hydrogen atom transfer to 1,2-silyl transfer." Nature Communications 12, no. 1 (2021). http://dx.doi.org/10.1038/s41467-021-22382-y.

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Abstract (sommario):
AbstractControlling the reactivity of reactive intermediates is essential to achieve selective transformations. Due to the facile 1,5-hydrogen atom transfer (HAT), alkoxyl radicals have been proven to be important synthetic intermediates for the δ-functionalization of alcohols. Herein, we disclose a strategy to inhibit 1,5-HAT by introducing a silyl group into the α-position of alkoxyl radicals. The efficient radical 1,2-silyl transfer (SiT) allows us to make various α-functionalized products from alcohol substrates. Compared with the direct generation of α-carbon radicals from oxidation of α-
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46

Budnikova, Yulia H., Egor L. Dolengovsky, Maxim V. Tarasov, and Tatyana V. Gryaznova. "Recent advances in electrochemical C—H phosphorylation." Frontiers in Chemistry 10 (November 3, 2022). http://dx.doi.org/10.3389/fchem.2022.1054116.

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Abstract (sommario):
The activation of C–H bond, and its direct one-step functionalization, is one of the key synthetic methodologies that provides direct access to a variety of practically significant compounds. Particular attention is focused on modifications obtained at the final stages of the synthesis of complicated molecules, which requires high tolerance to the presence of existing functional groups. Phosphorus is an indispensable element of life, and phosphorus chemistry is now experiencing a renaissance due to new emerging applications in medicinal chemistry, materials chemistry (polymers, flame retardant
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