Zeitschriftenartikel: „Carbon-Nitrozen bond(C-N) formation“

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Cataldo, Franco. „Cyanopolyynes: carbon chains formation in a carbon arc mimicking the formation of carbon chains in the circumstellar medium“. International Journal of Astrobiology 3, Nr. 3 (Juli 2004): 237–46. http://dx.doi.org/10.1017/s1473550404002149.

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Monocyanopolyynes and dicyanopolyynes can be synthesized quite easily by the submerged electric arc. Monocyanopolyynes having the general formula H[bond](C[triple bond]C)n[bond]C[triple bond]N can be synthesized together with ordinary polyynes series H[bond](C[triple bond]C)n[bond]H by arcing graphite electrodes in acetonitrile. Dicyanopolyynes N[triple bond]C[bond](C[triple bond]C)n[bond]C[triple bond]N are produced almost pure by arcing graphite electrodes directly into liquid nitrogen. These molecules are present in the envelope of post-AGB (asymptotic giant branch), carbon-rich giant stars and also in dark molecular clouds. They are incorporated into comets and also into other primitive materials and may play a role in the prebiotic synthesis of more complex organic molecules having a biological significance. Furthermore, the cyanopolyynes are involved in the atmospheric chemistry of some bodies of the solar system. The discovery of the easy formation of these molecules under laboratory conditions may explain why these molecules are so ubiquitous in space and may also stimulate new ideas about the mechanism of their formation.

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Kärkäs, Markus D. „Electrochemical strategies for C–H functionalization and C–N bond formation“. Chemical Society Reviews 47, Nr. 15 (2018): 5786–865. http://dx.doi.org/10.1039/c7cs00619e.

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3

Möhlmann, Lennart, Moritz Baar, Julian Rieß, Markus Antonietti, Xinchen Wang und Siegfried Blechert. „Carbon Nitride-Catalyzed Photoredox CC Bond Formation with N-Aryltetrahydroisoquinolines“. Advanced Synthesis & Catalysis 354, Nr. 10 (05.06.2012): 1909–13. http://dx.doi.org/10.1002/adsc.201100894.

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4

Li, Jing-Yuan, Qing-Wen Song, Kan Zhang und Ping Liu. „Catalytic Conversion of Carbon Dioxide through C-N Bond Formation“. Molecules 24, Nr. 1 (05.01.2019): 182. http://dx.doi.org/10.3390/molecules24010182.

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From the viewpoint of green chemistry and sustainable development, it is of great significance to synthesize chemicals from CO2 as C1 source through C-N bond formation. During the past several decade years, many studies on C-N bond formation reaction were involved, and many efforts have been made on the theory. Nevertheless, several great challenges such as thermodynamic limitation, low catalytic efficiency and selectivity, and high pressure etc. are still suffered. Herein, recent advances are highlighted on the development of catalytic methods for chemical fixation of CO2 to various chemicals through C-N bond formation. Meanwhile, the catalytic systems (metal and metal-free catalysis), strategies and catalytic mechanism are summarized and discussed in detail. Besides, this review also covers some novel synthetic strategies to urethanes based on amines and CO2. Finally, the regulatory strategies on functionalization of CO2 for N-methylation/N-formylation of amines with phenylsilane and heterogeneous catalysis N-methylation of amines with CO2 and H2 are emphasized.

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Kerru, Nagaraju, Suresh Maddila und Sreekantha B. Jonnalagadda. „Design of Carbon-carbon and Carbon-heteroatom Bond Formation Reactions under Green Conditions“. Current Organic Chemistry 23, Nr. 28 (17.01.2020): 3154–90. http://dx.doi.org/10.2174/1385272823666191202105820.

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: The development of C-C and C-heteroatom (C-N, C-O and C-P) bond reactions is a field of significant interest and has received momentous attention in modern organic chemistry. These reactions have been exploited in the synthesis of pharmaceuticals, agrochemicals and molecules of interest in materials science. With the increasing awareness of global warming and the use of renewable energies, it is of paramount importance to reduce the usage of hazardous chemicals in both industrial and academic research and to achieve a healthier environment through green practices. Green chemistry is a rapidly emerging approach that shows us a path for the sustainable growth of future science and technologies. In the recent past, healthy growth has been recorded in a number of organic reactions in aqueous media, which are environment-friendly and energy conserving. This review documents the literature on the development of green methodologies involving the design of C-C, C-O, C-N and C-P bond formations of coupling and condensed reactions. It emphasizes the exceptional practices and important advances achieved using alternative green tools, such as microwave (MW), high-speed ball milling (HSBM) and ultrasound irradiation techniques, and a variety of reusable catalysts and green solvents, with attention to water.

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Moehlmann, Lennart, Moritz Baar, Julian Riess, Markus Antonietti, Xinchen Wang und Siegfried Blechert. „ChemInform Abstract: Carbon Nitride-Catalyzed Photoredox C-C Bond Formation with N-Aryltetrahydroisoquinolines.“ ChemInform 43, Nr. 50 (29.11.2012): no. http://dx.doi.org/10.1002/chin.201250155.

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7

Kamanna, Kantharaju, und Santosh Y. Khatavi. „Microwave-accelerated Carbon-carbon and Carbon-heteroatom Bond Formation via Multi-component Reactions: A Brief Overview“. Current Microwave Chemistry 7, Nr. 1 (23.06.2020): 23–39. http://dx.doi.org/10.2174/2213346107666200218124147.

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Multi-Component Reactions (MCRs) have emerged as an excellent tool in organic chemistry for the synthesis of various bioactive molecules. Among these, one-pot MCRs are included, in which organic reactants react with domino in a single-step process. This has become an alternative platform for the organic chemists, because of their simple operation, less purification methods, no side product and faster reaction time. One of the important applications of the MCRs can be drawn in carbon- carbon (C-C) and carbon-heteroatom (C-X; X = N, O, S) bond formation, which is extensively used by the organic chemists to generate bioactive or useful material synthesis. Some of the key carbon- carbon bond forming reactions are Grignard, Wittig, Enolate alkylation, Aldol, Claisen condensation, Michael and more organic reactions. Alternatively, carbon-heteroatoms containing C-N, C-O, and C-S bond are also found more important and present in various heterocyclic compounds, which are of biological, pharmaceutical, and material interest. Thus, there is a clear scope for the discovery and development of cleaner reaction, faster reaction rate, atom economy and efficient one-pot synthesis for sustainable production of diverse and structurally complex organic molecules. Reactions that required hours to run completely in a conventional method can now be carried out within minutes. Thus, the application of microwave (MW) radiation in organic synthesis has become more promising considerable amount in resource-friendly and eco-friendly processes. The technique of microwaveassisted organic synthesis (MAOS) has successfully been employed in various material syntheses, such as transition metal-catalyzed cross-coupling, dipolar cycloaddition reaction, biomolecule synthesis, polymer formation, and the nanoparticle synthesis. The application of the microwave-technique in carbon-carbon and carbon-heteroatom bond formations via MCRs with major reported literature examples are discussed in this review.

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Yang, Zhen-Zhen, Liang-Nian He, Jiao Gao, An-Hua Liu und Bing Yu. „Carbon dioxide utilization with C–N bond formation: carbon dioxide capture and subsequent conversion“. Energy & Environmental Science 5, Nr. 5 (2012): 6602. http://dx.doi.org/10.1039/c2ee02774g.

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Currie, Lucy, Luca Rocchigiani, David L. Hughes und Manfred Bochmann. „Carbon–sulfur bond formation by reductive elimination of gold(iii) thiolates“. Dalton Transactions 47, Nr. 18 (2018): 6333–43. http://dx.doi.org/10.1039/c8dt00906f.

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Ni, Jing, und Xi Ping Hao. „Carbon Nitride Films Prepared by PECVD in CH₄-NH₃ Precursor“. Advanced Materials Research 538-541 (Juni 2012): 124–27. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.124.

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Carbon nitride (CNx) films were fabricated by plasma enhanced chemical vapor deposition technology in methane-ammonia system, in which the plasma was excited by the hollow cathode glow discharge. The composition，microstructure and hardness of the deposited films were investigated by measurements employing X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and nano-indentation experiment. The results indicate that the nitrogen content in the film varies from 4.2 to 8.6 at.% and the nitrogen atoms are bonded to carbon atoms through C-N, C=N and C≡N bonds. Furthmore, higher nitrogen content is in favor of the formation of C-N bond, which may enhance the film hardness.

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Lv, Ze-Jie, Junnian Wei, Wen-Xiong Zhang, Ping Chen, Dehui Deng, Zhang-Jie Shi und Zhenfeng Xi. „Direct transformation of dinitrogen: synthesis of N-containing organic compounds via N−C bond formation“. National Science Review 7, Nr. 10 (23.06.2020): 1564–83. http://dx.doi.org/10.1093/nsr/nwaa142.

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Abstract N-containing organic compounds are of vital importance to lives. Practical synthesis of valuable N-containing organic compounds directly from dinitrogen (N2), not through ammonia (NH3), is a holy-grail in chemistry and chemical industry. An essential step for this transformation is the functionalization of the activated N2 units/ligands to generate N−C bonds. Pioneering works of transition metal-mediated direct conversion of N2 into organic compounds via N−C bond formation at metal-dinitrogen [N2-M] complexes have generated diversified coordination modes and laid the foundation of understanding for the N−C bond formation mechanism. This review summarizes those major achievements and is organized by the coordination modes of the [N2-M] complexes (end-on, side-on, end-on-side-on, etc.) that are involved in the N−C bond formation steps, and each part is arranged in terms of reaction types (N-alkylation, N-acylation, cycloaddition, insertion, etc.) between [N2-M] complexes and carbon-based substrates. Additionally, earlier works on one-pot synthesis of organic compounds from N2 via ill-defined intermediates are also briefed. Although almost all of the syntheses of N-containing organic compounds via direct transformation of N2 so far in the literature are realized in homogeneous stoichiometric thermochemical reaction systems and are discussed here in detail, the sporadically reported syntheses involving photochemical, electrochemical, heterogeneous thermo-catalytic reactions, if any, are also mentioned. This review aims to provide readers with an in-depth understanding of the state-of-the-art and perspectives of future research particularly in direct catalytic and efficient conversion of N2 into N-containing organic compounds under mild conditions, and to stimulate more research efforts to tackle this long-standing and grand scientific challenge.

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Chen, Wei, Tingzhen Li und Xinwen Peng. „Visible-light-promoted thiocyanation of sp2 C–H bonds over heterogeneous graphitic carbon nitrides“. New Journal of Chemistry 45, Nr. 31 (2021): 14058–62. http://dx.doi.org/10.1039/d1nj00532d.

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Dasgupta, Rajarshi, Atanu Panda, Shiv Pal, Puthan Veetil Muhasina, Susmita De, Pattiyil Parameswaran und Shabana Khan. „Catalyst free boron carbon bond cleavage and facile formation of five-membered PNBCC heterocycles“. Dalton Transactions 46, Nr. 44 (2017): 15190–94. http://dx.doi.org/10.1039/c7dt03565a.

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The [3 + 2] cycloaddition reaction of N(2,6-iPr₂C₆H₃)(PPh₂)(BCy₂) (1) with activated alkynes led to the boron, phosphorus containing five-membered heterocycles (2–4) with facile cleavage of B–C bond and concomitant formation of a P–C bond with an ylidic character.

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Singh, Laimujam Sidartha, Arup K. Kabi, Ragini Sengupta, Anupam Roy, Abhishek Sahoo, Indranil Saha und Chandi C. Malakar. „C-H Functionalization and C-N Bond Formation Approaches under Catalytic Conditions for the Synthesis of α-Ketoamides and 2,4-Disubstituted-1,3,5-triazines“. Asian Journal of Chemistry 34, Nr. 7 (2022): 1841–47. http://dx.doi.org/10.14233/ajchem.2022.23769.

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This work describes an easy way to perform approach for the transformation of arylmethyl ketones to α-ketoamides using secondary amines as starting materials in the presence of iodine as a catalyst in water under peroxide free reaction conditions. The established amidation reaction proceeds via α-C(sp3)-H functionalization and C-N bond formation approaches in water at ambient temperature. On the other hand, a novel and straightforward synthesis of 2,4-disubstituted-1,3,5-triazines via nickel-catalyzed cyclization of amidines with DMSO as one-carbon synthon has been developed. The developed strategy proceeds via C-N bond formation.

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Wang, Jian, Necip Berker Uner, Scott Edwin Dubowsky, Matthew Phelan Confer, Rohit Bhargava, Yunyan Sun, Yuting Zhou, Mohan Sankaran und Jeffrey S. Moore. „Plasma Electrochemistry for Carbon-Carbon Bond Formation Via Pinacol Coupling Reaction“. ECS Meeting Abstracts MA2023-01, Nr. 20 (28.08.2023): 1512. http://dx.doi.org/10.1149/ma2023-01201512mtgabs.

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Low-temperature, atmospheric-pressure plasmas in contact with liquids have attracted interest for various chemical applications including the degradation of organic pollutants,1 conversion of abundant feedstocks,2,3 and more recently, organic chemistry.4 Compared to other chemical approaches, plasma-liquid chemistry does not require a catalyst material, is electrified, and produces unique reactive species such as solvated electrons, one of the strongest chemical reducing species.5 Here, we present an application of plasma-liquid chemistry to the formation of carbon-carbon bonds via the well-known pinacol coupling reaction. Pinacol coupling is conventionally carried out by using an electron donating reagent such as magnesium to initially reduce a carbonyl group forming a ketyl radical anion species. A pair of these ketyl groups then react to form a vicinal diol, which in the presence of a proton donor such as water, leads to the final diol product. We show that the pinacol coupling reaction can instead be driven at a plasma-liquid interface without any catalyst. Our study was performed using a direct-current (DC) powered plasma formed between a metal electrode and liquid water surface similar to previous reports.2 Parametric studies were focused on methyl-4-formylbenzoate (MFB) as the substrate. We find that the faradaic efficiency of the pinacol product depends on the initial concentration, increasing from 20% to 80% as the concentration increased from 0.06 M to 0.18 M. For an initial concentration of 0.12 M and a constant operating current of 3 mA, a yield of 46% can be reached after 12 h. The experimental results were supported by a reaction-diffusion model, and a rate constant of 10^10 L-1 mol-1 s-1 was extracted from kinetic studies. In addition to the pinacol product, nuclear magnetic resonance (NMR) spectroscopy also indicated methyl 4-(dimethoxymethyl)benzoate, methyl 4-(hydroxymethyl)benzoate, and 4-(methoxycarbonyl)benzoic acid as side products. By carrying out scavenger control experiments, we show that the vicinal diol is produced by solvated electron reduction while these other side products are formed by reactions with other radicals or the solvent. The generality of the approach is demonstrated by extending to several other aromatic aldehydes and ketones. References: Nau-Hix, C., Multari, N., Singh R. K., Richardson, S., Kulkarni, P., Anderson, R. H., Holsen, T. M., and Mededovic Thagard, S. ACS EST Water 1, 680-687 (2021). Hawtof, R., Ghosh, S., Guarr, E., Xu, C., Sankaran, R. M., and Renner, J. N. Adv. 5, eaat5778 (2019). Toth, J. R., Abuyazid, N. H., Lacks,D. J., Renner, J. N., and Sankaran, R. M. ACS Sustain. Chem. Eng. 8, 14845-14854 (2020). Xu, H., Wang, S., Shaban, M., Montazersadgh, F., Alkayal, A., Liu, D., Kong, M. G., Buckley, B., Iza, F. Plasma Process Polym. 17, 1900162 (2019). Rumbach, P., Bartels, D. M., Sankaran, R. M., Go, D. B. Nat. Comm.6, 7248 (2015). Figure 1

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Li, Ting, Lei Yang, Kaidong Ni, Zhenyu Shi, Fei Li und Dongyin Chen. „An efficient approach to construct benzisothiazol-3(2H)-ones via copper-catalyzed consecutive reaction of 2-halobenzamides and carbon disulfide“. Organic & Biomolecular Chemistry 14, Nr. 26 (2016): 6297–303. http://dx.doi.org/10.1039/c6ob00819d.

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An efficient copper-catalyzed reaction for the synthesis of benzisothiazol-3(2H)-ones has been developed, starting from easily available 2-halobenzamides and carbon disulfide. The reaction proceeds via a consecutive process with S–C bond and S–N bond formation.

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KHASHAN, KHAWLA S., und MAYYADAH H. MOHSIN. „CHARACTERIZATION OF CARBON NITRIDE NANOPARTICLES PREPARED BY LASER ABLATION IN LIQUID FOR OPTOELECTRONIC APPLICATION“. Surface Review and Letters 22, Nr. 04 (15.06.2015): 1550055. http://dx.doi.org/10.1142/s0218625x15500559.

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In this work, carbon nitride ( C 3 N 4) nanoparticles (NPs) were synthesized by pulse laser ablation of graphite in ammonium solution, and deposited on silicon substrates by spray. Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometer and transmission electron microscopy (TEM) were used to study bonding, absorption, size and morphology of the produce NPs. The FTIR absorption peaks at 2121.6, 1631.7 and 1384 cm-1 stretching vibration bond, it is inferred for the C ≡ N , C = N and C – N , respectively. Bonds suggests the formation, C 3 N 4 NPs. UV absorption peaks coincide with the electronic transitions corresponding to the formation, C 3 N 4 NPs with 3.98 eV optical bandgap. The TEM show the aggregation of the C 3 N 4 NPs with size ranges from 4 to 83 nm, and also the leaf-like structure are shown in the structure of C 3 N 4 suspension. High performance rectifying C 3 N 4/ Si heterojunction with a rectifying ratio exceeding 345 at V = 5 V was obtained, with high photoresponsivity of 2.33 A/W at 600 nm.The results show that C 3 N 4 NPs on silicon substrates will act as very good candidates for making high efficiency photodiodes.

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Uhl, Werner, und Madhat Matar. „Hydroalumination of Nitriles and Isonitriles“. Zeitschrift für Naturforschung B 59, Nr. 11-12 (01.12.2004): 1214–22. http://dx.doi.org/10.1515/znb-2004-11-1239.

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Abstract Hydroalumination of H5C6-C≡N with di(tert-butyl)aluminum hydride 1or the corresponding diethyl compound 2yielded the products tBu2Al-N=C(C6H5)H 3and Et2Al-N=C(C6H5)H 4, respectively, both of which form dimers possessing Al2N2 heterocycles with two exocyclic C=N double bonds. NMR spectroscopic data indicate the occurrence of cis/trans isomers in solutions of compound 4. The dimerization of the imide via Al-N interactions was prevented by employing the hydride [(Me3Si)2HC]2AlH 6bearing the bulky bis(trimethylsilyl)methyl substituents. Its reaction with benzonitrile yielded the compound R2Al-N=C(C6H5)H(N≡C-C6H5) 7[R = CH(SiMe3)2], in which the coordinative saturation of the aluminum atoms was achieved by adduct formation with one molecule of the starting nitrile. In these cases the C≡N triple bond inserted completely into the Al-H bond of the hydride. In contrast, the reaction of tert-butyl isonitrile afforded the product tBu2Al-C(H)=NC6H5 8by the insertion of its terminal carbon atom into the Al-H bond. Hence, it has a geminal arrangement of the aluminum and hydrogen atoms. Dimerization of 8yielded a six-membered heterocycle. Hydroalumination does not occur upon treatment of the hydride 1with trimethylsilylnitrile. Instead, the Si-CN bond was cleaved, and the aluminum cyanide (tBu2Al-C≡N)4 9was isolated in a high yield.

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Chen, Pu, Huawen Huang, Qi Tan, Xiaochen Ji und Feng Zhao. „Recent Advances in Molecule Synthesis Involving C-C Bond Cleavage of Ketoxime Esters“. Molecules 28, Nr. 6 (15.03.2023): 2667. http://dx.doi.org/10.3390/molecules28062667.

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The synthetic strategies of oxime derivatives participating in radical-type reactions have been rapidly developed in the last few decades. Among them, the N–O bond cleavage of oxime esters leading to formation of nitrogen-centered radicals triggers adjacent C–C bond cleavage to produce carbon-centered free radicals, which has been virtually used in organic synthesis in recent years. Herein, we summarized the radical reactions involving oxime N–O bond and C–C bond cleavage through this special reaction form, including those from acyl oxime ester derivatives and cyclic ketoxime ester derivatives. These contents were systematically classified according to different reaction types. In this review, the free radical reactions involving acyl oxime esters and cyclic ketoxime esters after 2021 were included, with emphasis on the substrate scope and reaction mechanism.

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Chipanina, N. N., L. P. Oznobikhina und N. F. Lazareva. „n-(chlorodimethylsilyl)methylated derivatives of N,N′-propyleneurea. ir spectra analysis and quantum-chemical calculations“. Журнал общей химии 93, Nr. 5 (15.05.2023): 730–40. http://dx.doi.org/10.31857/s0044460x23050086.

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The IR spectra of N -silylmethylated derivatives of N , N ′-propyleneurea in solvents of different polarity were studied in a wide temperature range. The DFT method was used to perform quantum chemical calculations of geometric, energy and spectral characteristics of these compounds in isolated state (gas) and polar medium (DMSO). Analysis and comparison of these results made it possible to evaluate the influence of the environment on the criteria for the formation and strength of intramolecular dative C=O→Si bonds. The dependence of the dative bond О→Si and the order of the bonds C=O and C-N, including of the carbon atom of the C=O group, on the interaction energy of the LEP of the oxygen atom of the carbonyl group with σ*-orbitals of axial Si-Cl ax and C-N bonds, as well as interactions of LEP of nitrogen atoms with σ*-orbitals of the C=O and C-N bonds.

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Wan, Jie-Ping, und Yanfeng Jing. „Recent advances in copper-catalyzed C–H bond amidation“. Beilstein Journal of Organic Chemistry 11 (17.11.2015): 2209–22. http://dx.doi.org/10.3762/bjoc.11.240.

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Copper catalysis has been known as a powerful tool for its ubiquitous application in organic synthesis. One of the fundamental utilities of copper catalysis is in the C–N bond formation by using carbon sources and nitrogen functional groups such as amides. In this review, the recent progress in the amidation reactions employing copper-catalyzed C–H amidation is summarized.

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Ahmadi, Mohammad Taghi, Ahmad Razmdideh, Seyed Saeid Rahimian Koloor und Michal Petrů. „Carbon-Based Band Gap Engineering in the h-BN Analytical Modeling“. Materials 13, Nr. 5 (25.02.2020): 1026. http://dx.doi.org/10.3390/ma13051026.

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The absence of a band gap in graphene is a hindrance to its application in electronic devices. Alternately, the complete replacement of carbon atoms with B and N atoms in graphene structures led to the formation of hexagonal boron nitride (h-BN) and caused the opening of its gap. Now, an exciting possibility is a partial substitution of C atoms with B and N atoms in the graphene structure, which caused the formation of a boron nitride composite with specified stoichiometry. BC2N nanotubes are more stable than other triple compounds due to the existence of a maximum number of B–N and C–C bonds. This paper focused on the nearest neighbor’s tight-binding method to explore the dispersion relation of BC2N, which has no chemical bond between its carbon atoms. More specifically, the band dispersion of this specific structure and the effects of energy hopping in boron–carbon and nitrogen–carbon atoms on the band gap are studied. Besides, the band structure is achieved from density functional theory (DFT) using the generalized gradient approximations (GGA) approximation method. This calculation shows that this specific structure is semimetal, and the band gap energy is 0.167 ev.

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Foley, Nicholas A, T. Brent Gunnoe, Thomas R Cundari, Paul D Boyle und Jeffrey L Petersen. „Activation of sp3 Carbon–Hydrogen Bonds by a Ruthenium(II) Complex and Subsequent Metal-Mediated CC and CN Bond Formation“. Angewandte Chemie International Edition 47, Nr. 4 (11.01.2008): 726–30. http://dx.doi.org/10.1002/anie.200704614.

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Foley, Nicholas A, T. Brent Gunnoe, Thomas R Cundari, Paul D Boyle und Jeffrey L Petersen. „Activation of sp3 Carbon–Hydrogen Bonds by a Ruthenium(II) Complex and Subsequent Metal-Mediated CC and CN Bond Formation“. Angewandte Chemie 120, Nr. 4 (11.01.2008): 738–42. http://dx.doi.org/10.1002/ange.200704614.

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Buncel, Erwin, und Julian M. Dust. „Ambident reactivity in the reaction of phenoxide ion with 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, new superelectrophiles“. Canadian Journal of Chemistry 66, Nr. 7 (01.07.1988): 1712–19. http://dx.doi.org/10.1139/v88-277.

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Reaction of the novel superelectrophiles 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, 3, and 4, possessing two electrophilic centres, with the ambident nucleophile potassium phenoxide in (CD3)2SO was followed by 400 MHz 1H nuclear magnetic resonance spectroscopy. A dichotomy in the reaction pathways has been observed. With MeO−, attack at C-7 leads to reversible adduct formation, while attack at C-1′ results in irreversible N-2: C-1′ bond scission via the metastable C-1′ adduct. In contrast, the reaction of 3 and 4 with PhO− proceeds by a two-pronged attack: formation of C-7 carbon-bonded phenoxide adducts via the ortho and para carbon sites, and oxygen-based cleavage products by attack at the C-1′ position, accompanied by N-2:C-1′ bond scission, in accord with the ambident reactivity of PhO−. Significantly, in this case reaction of both C-7 and C-1′ is effectively irreversible. Moreover, the reaction of phenoxide with either 3 or 4 shows striking differences compared to the reaction of PhO− with 2-N-(picryl)-4,6-dinitrobenzotriazole 1-oxide, 1. Reaction of PhO− with 1 resulted only in O-attack at C-1′ and N-2:C-1′ bond scission; there was no evidence for C-7 adduct formation via O- or C-attack. This marked difference in behaviour can be attributed to the decreased susceptibility to C-1′ attack exhibited by 3 and 4 as compared to 1 and arises from the successive removal of electron-withdrawing nitro groups from the 2-N′-nitroaryl moiety in the series 1 → 3 → 4. The reactions are discussed on the basis of selectivity considerations and an activation energy/reaction coordinate profile comparing the pathways for both C-attack at C-7 and O-attack at C-l′ as electrophilicity (delocalizability) is progressively modulated in the reaction series.

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Bartz, Ricardo H., Luiz H. Dapper, Jean C. Kazmierczak, Ricardo F. Schumacher, Gelson Perin, Samuel Thurow, Filipe Penteado und Eder J. Lenardão. „Lighting Up the Organochalcogen Synthesis: A Concise Update of Recent Photocatalyzed Approaches“. Catalysts 13, Nr. 3 (03.03.2023): 520. http://dx.doi.org/10.3390/catal13030520.

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This review describes the recent advances in photocatalyzed reactions to form new carbon–sulfur and carbon–selenium bonds. With a total of 136 references, of which 81 articles are presented, the authors introduce in five sections an updated picture of the state of the art in the light-promoted synthesis of organochalcogen compounds (from 2019 to present). The light-promoted synthesis of sulfides by direct sulfenylation of C–C π-bonds; synthesis of sulfones; the activation of Csp2–N bond in the formation of Csp2–S bonds; synthesis of thiol ester, thioether and thioacetal; and the synthesis of organoselenium compounds are discussed, with detailed reaction conditions and selected examples for each protocol.

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DEVI, REENA, und RANJAN KUMAR. „STRUCTURE AND STABILITY OF ENDOHEDRAL Cn@C60“. Modern Physics Letters B 24, Nr. 12 (20.05.2010): 1255–66. http://dx.doi.org/10.1142/s0217984910023190.

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We report ab initio molecular dynamics simulations of carbon clusters in free space and inside C 60 using SIESTA. We have studied the stability and geometries of small carbon clusters consisting of 2–12 carbon atoms inside the C 60 molecule and in free space by optimizing the atomic geometries. We have found that the C – C bond length is in agreement with the 1.40 and 1.45 values reported earlier. We find that the clusters inside the C 60 are more stable than clusters in free space. Binding energy per carbon atom initially increases with number of carbon atoms in the cluster and then decreases after maximizing for the 9-atom cluster. For more than 9 carbon atoms in the cluster inside C 60, C atoms of the cluster start forming bond with the C 60 cage and the C 60 structure gets distorted. We have done calculations for charge transfer and chemical reactivity. The calculations of ionization potential and electron affinity show that clusters in free space are less reactive compared with C n@ C 60. Charge transfer calculations show that the bond formation of C atoms with the C 60 cage is accompanied with a transfer of charge from carbon cluster to C 60.

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Zhang, Cong, Ling Qu und Wenjie Yuan. „Effects of Si/C Ratio on the Phase Composition of Si-C-N Powders Synthesized by Carbonitriding“. Materials 13, Nr. 2 (12.01.2020): 346. http://dx.doi.org/10.3390/ma13020346.

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Si-C-N based materials possess interesting properties such as high hardness and oxidation resistance. The compacts of silicon and cornstarch with different Si/C ratios were subjected to carbonitriding at 1350–1550 °C. Reaction products were characterized by X-ray powder diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effects of Si/C ratio on the phase composition of Si-C-N powders were investigated. The results revealed that the Si/C ratio played a crucial role on the formation of crystalline silicon carbonitride (SiCN) and the phase composition of Si-C-N powders. It was demonstrated that liquid silicon is an important medium and reaction site for the introduction of nitrogen, so the Si content in reactants has affected the N content in the product. On the other hand, carbon participates in the carbonization of Si3N4 and the formation of SiC. The contents of C-N bond and SiCN in the products are carbon content-dependent. Combining the above two aspects, the maximum yield of SiCN can be achieved with the Si/C ratio of 1:1 to 1:1.5.

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QIU, AIMIN, und DONALD T. SAWYER. „The Electrochemical Evaluation of the Metal-Carbon Bond Energies (−ΔGBF) of Alkylated Iron and Cobalt Porphyrins [(por)M-R]“. Journal of Porphyrins and Phthalocyanines 01, Nr. 02 (April 1997): 125–34. http://dx.doi.org/10.1002/(sici)1099-1409(199704)1:2<125::aid-jpp15>3.0.co;2-x.

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The electron-transfer oxidation-reduction chemistry for the alkyl derivatives of iron and cobalt porphyrins [( por ) M III − R ] has been characterized on the basis of cyclic voltammetric and controlled-potential-electrolysis measurements. The electrogenerated anions of iron and cobalt porphyrins [( por ) M − and ( por −·) M −] are strong nucleophiles that react with alkyl halides ( RX ) via a nucleophilic displacement process to form metal-carbon bonds [( por ) M - R and ( por −·) M - R ]. The difference in the reduction potentials for RX and ( por ) M II provides an approximate measure of the ( por ) M - R bond-formation free energy (−ΔG BF ). The −ΔG BF values for iron porphyrins (14–35 kcal mol−1) and for cobalt porphyrins (20-38 kcal mol−1) depend on the electron density of the porphyrin ring ( OEP > TPP > Cl 8 TPP > F 20TPP) and the structure of the alkyl group (1° > 2° > 3°). Thus, the apparent metal-carbon bond energy (−ΔG BF ) for ( OEP ) Fe III- Bu -n is 28 ± 2 kcal mol−1, and for [( MeO )4 TPP ] Co III- Bu -n is 36 ± 2 kcal mol −1. The ( por −·) M − dianions react with carbon dioxide in an electrocatalysed reduction cycle to give CO and CO 32− via the apparent transient formation of a metal-carbon bond [( por −·) M - C ( O ) O −; −Δ G BF ≥ 12 kcal mol −1 for iron porphyrins].

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Filkina, Maria E., Daria N. Baray, Elena K. Beloglazkina, Yuri K. Grishin, Vitaly A. Roznyatovsky und Maxim E. Kukushkin. „Regioselective Cycloaddition of Nitrile Imines to 5-Methylidene-3-phenyl-hydantoin: Synthesis and DFT Calculations“. International Journal of Molecular Sciences 24, Nr. 2 (09.01.2023): 1289. http://dx.doi.org/10.3390/ijms24021289.

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Nitrile imine cycloaddition to hydantoins containing an exocyclic C=C double bond has been previously described in a very limited number of examples. In this work, regioselective synthesis of spiro-pyrazoline-imidazolidine-2,4-diones based on a 1,3-dipolar cycloaddition reaction of nitrile imines to 5-methylidene-3-phenyl-hydantoin have been proposed. It was found that, regardless of the nature of the aryl substituents at the terminal C and N atoms of the C-N-N fragment of nitrile imine (electron donor or electron acceptor), cycloaddition to the 5-methylidenhydantoin exocyclic C=C bond proceeds regioselectively, and the terminal nitrogen atom of the nitrile imine connects to the more sterically hindered carbon atom of the double bond, which leads to the formation of a 5-disubstituted pyrazoline ring. The observed cycloaddition regioselectivity was rationalized using DFT calculations of frontier molecular orbital interactions, global CDFT reactivity indices, and minimum energy paths.

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Nossa, A., und A. Cavaleiro. „Chemical and physical characterization of C(N)-doped W–S sputtered films“. Journal of Materials Research 19, Nr. 8 (August 2004): 2356–65. http://dx.doi.org/10.1557/jmr.2004.0293.

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The load-bearing capacity of self-lubricating W–S films can be improved by doping with nitrogen or carbon. In this study, the chemical composition, the atomic bonding, the structure, and the surface and cross section morphologies of sputtered W–S–C(N) films were analyzed. The addition of the doping element leads to a progressive broadening of the x-ray diffraction (XRD) peaks indicating a loss of crystallinity. In W–S–N films, amorphous structure could be obtained. In W–S–C films, W–C compounds were detected in conjunction with the hexagonal WS2 phase. For the highest C contents, a nanocomposite structure, including those phases and graphite, was suggested for the film. X-ray photoelectron spectroscopy results showed different types of bonds in the W4f peak in good agreement with the XRD results, i.e., when W–C(N) compounds were indexed W–S, W–C, and W–N bonds are present in the W4f peak. For the highest C content film, the detection of C–C bond in the C1s peak confirmed the formation of graphite.

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Tilgner, Dominic, Mara Klarner, Sebastian Hammon, Martin Friedrich, Andreas Verch, Niels de Jonge, Stephan Kümmel und Rhett Kempe. „H2-Generation from Alcohols by the MOF-Based Noble Metal-Free Photocatalyst Ni/CdS/TiO2@MIL-101“. Australian Journal of Chemistry 72, Nr. 10 (2019): 842. http://dx.doi.org/10.1071/ch19255.

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The synthesis of important classes of chemical compounds from alcohols helps to conserve Earth’s fossil carbon resources, since alcohols can be obtained from indigestible and abundantly available biomass. The utilisation of visible light for the activation of alcohols permits alcohol-based C–N and C–C bond formation under mild conditions inaccessible with thermally operating hydrogen liberation catalysts. Herein, we report on a noble metal-free photocatalyst able to split alcohols into hydrogen and carbonyl compounds under inert gas atmosphere without the requirement of electron donors, additives, or aqueous reaction media. The reusable photocatalyst mediates C–N multiple bond formation using the oxidation of alcohols and subsequent coupling with amines. The photocatalyst consists of a CdS/TiO2 heterojunction decorated with co-catalytic Ni nanoparticles and is prepared on size-optimised colloidal metal–organic framework (MOF) crystallites.

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Smith, DW. „Electronegativity Equilibration and the Methylene Increment in Organic Thermochemistry“. Australian Journal of Chemistry 48, Nr. 1 (1995): 65. http://dx.doi.org/10.1071/ch9950065.

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It is proposed that the magnitude of the ' methylene increment' ∆∆ fH°(CnH2n+1X, Cn+1H2n+3X) between the heats of formation of successive members of a homologous series can be rationalized by considering the variation of carbon-carbon bond enthalpies Eij. These are deemed to be related to the products qiqj of the fractional charges on adjacent carbon atoms by the relation: Eij=E°-aqiqj where E° and a are empirical constants, and the fractional charges are estimated by electronegativity equilibration. For the homologous series CnH2n+1X (X = H, Cl , Br, I, OH, OMe , NH2), a linear correlation is found between the mean increment [∆∆ fH °(CH3X, CnH2n+1)]/(n-1) and the mean charge product ∑qiqj/(n - 1). The empirically obtained value for E° is in close agreement with the experimental C-C bond enthalpy in diamond. For all series, the calculated methylene increment converges to a common value of 20.6 kJ mol-1. The treatment may provide an attractive alternative to existing methods for the estimation of the heats of formation of organic compounds, requiring fewer empirical parameters.

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Hung, Chen-Hsiung, Chia-Chi Liaw, Wei-Ming Chin, Gao-Fong Chang und Chuan-Hung Chuang. „Nitric acid promoted formation of an N-confused porphyrin-derived porphodimethene and a violinoid“. Journal of Porphyrins and Phthalocyanines 10, Nr. 07 (Juli 2006): 953–61. http://dx.doi.org/10.1142/s1088424606000284.

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The nitration of free-base N -confused porphyrin led to a novel 5,10-meso-dihydroxy- N -confused porphodimethene and an open-ring N -confused violinoid. The results support nitration occurring first, followed by nucleophilic addition of a hydroxyl group and a parallel reaction of oxygenolysis to cause the ring-opening. The nitro group substituted at the inner carbon of the inverted pyrrole ring is located on both the porphodimethene and violinoid. In the case of the porphodimethene, two dihydroxyl groups with υ( OH ) at 3404 cm−1 are arranged in a syn conformation at the same side with the nitro group. The violinoid exhibits υ( C = O ) at 1659 cm−1. NMR and structure determination suggest that oxygenolysis occurs selectively at the C=C bond between the α-pyrrole and meso carbon closest to the amino NH of the inverted pyrrole ring. The single crystal structure of porphodimethene gave a 50% disorder between the peripheral nitrogen and carbon atom on the inverted pyrrole ring, while a dimeric structure assembled through hydrogen bonding interactions was observed in the crystal lattice of the violinoid.

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Tajbakhsh, Mahmood, Ali Ramezani, Mohammad Qandalee, Mobina Falahati, Carlos J. Durán-Valle, Silvia Izquierdo und Ignacio M. López-Coca. „Carbon–Heteroatom Bond Formation via Coupling Reactions Performed on a Magnetic Nanoparticle Bed“. AppliedChem 1, Nr. 2 (04.10.2021): 75–89. http://dx.doi.org/10.3390/appliedchem1020007.

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Cross-coupling reactions leading to carbon–heteroatom bonds yield compounds that attract substantial interest due to their role as structural units in many synthetic protocols for bioactive and natural products. Therefore, many research works aim at the improvement of heterogeneous catalytic protocols. We have studied the use of magnetite nanoparticles and solid base compounds in organic synthetic reactions in carbon–heteroatom bond formation because they can be flocculated and dispersed, and reversibly controlled by applying a magnetic field. In this work, we have developed an efficient and simple synthetic approach for the C–O/C–N cross-coupling reaction under ligand-free conditions by using CuI as a catalyst and KF/Fe3O4 as a base. We performed the nucleophilic aromatic substitution of electron-deficient aryl halides and phenols. It was found that both the solvent nature and the base have a profound influence on the reaction process. This approach affords good to excellent yields of arylated products. KF/Fe3O4 displayed convenient magnetic properties and could be easily separated from the reaction using a magnet and recycled several times without significant loss of catalytic activity. This method has been successfully investigated for the Ullmann coupling reaction.

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Choi, Soo Young, und Young Keun Chung. „N-Heterocyclic Carbene (NHC)-Rhodium-Catalyzed Carbonylative CC Bond Formation of Allenols with Arylboronic Acids under Carbon Monoxide“. Advanced Synthesis & Catalysis 353, Nr. 14-15 (Oktober 2011): 2609–13. http://dx.doi.org/10.1002/adsc.201100309.

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Chipanina, N. N., L. P. Oznobikhina, I. V. Ushakova und B. A. Shainyan. „Mechanism of chlorotriflamidation of vinylsilanes with N,N-dichlorotriflamide“. Журнал общей химии 93, Nr. 3 (15.03.2023): 425–31. http://dx.doi.org/10.31857/s0044460x23030101.

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The mechanism of the reaction of vinylsilanes with N , N -dichlorotriflamide and the effect of a substituent at the silicon atom on the reaction course and on the charge distribution in substrates and their carbon analogues were studied by DFT method. The C=C bond in vinylsilanes and alkenes is polarized in the opposite way. The reaction proceeds in two stages: chlorination of the substrate with the formation of a chloronium ion, and its opening at the Cβ-Cl bond by the N -chlorotriflamide anion. Transition states of two stages were calculated. The reaction products are hydrolyzed to NH-derivatives; their IR spectra and supramolecular structure, including cyclic and linear dimers, calculated in the gas phase and in a polar medium, were studied.

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Kaur, Sandeep, Hitesh Sharma und Isha Mudahar. „Understanding the Interaction Between Fullerene and Graphene Nanoribbons Using Density Functional Theory“. ECS Transactions 107, Nr. 1 (24.04.2022): 19863–74. http://dx.doi.org/10.1149/10701.19863ecst.

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Carbon based heterostructures are extremely important in the field of material science as the junction of two carbon nanomaterials strongly influence the properties of a material. In present work, the structural, electronic and magnetic properties of covalently attached C60 cage with armchair and zigzag GNRs have been investigated using density functional theory. AGNR-nanobuds don't form stable structures, owing to their positive values of the interaction energy. However, pure and N/B doped ZGNR-nanobud form stable structures with [2+2]hhT mode, hence presenting the possibility of their formation. Average diameter for N doped ZGNR-nanobuds decreases as the C-N bond length is lower than the C-C bond length whereas average diameter for doped ZGNR increases due to the large C-B bond length. The considered complexes are magnetic in nature having a finite value of total magnetic moment. Increase in total magnetic moment is due to the induced localized magnetic moments near dopant sites, whereas decrease in the total magnetic moments is due to the reduction in magnetic moments at C-sites near connecting bond atoms. The significant variation in electronic density of states near the Fermi level leads to change in the metallic behaviour of ZGNR-nanobuds. Mulliken charge analysis shows that in N-doped nanobud, there is a transfer of charge from N to surrounding C atoms due to their electronegativity difference, and there is a gain in charge of B from surrounding C atoms. The unique electronic and magnetic properties of nanobuds can lead to the possible applications in the field of magnetic nano devices.

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Naveen, Kanagaraj, Avanashiappan Nandakumar und Paramasivan Perumal. „Synthesis of 4-Alkylidene-Substituted 1,2,3,4-Tetrahydroisoquinolines via Palladium-Catalyzed Carbopalladation/C–H Activation of 2-Bromobenzyl-N-propargylamines“. Synthesis 47, Nr. 11 (18.03.2015): 1633–42. http://dx.doi.org/10.1055/s-0034-1380414.

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Tetrasubstituted alkene-based 1,2,3,4-tetrahydroisoquinolines are synthesized via the formation of a cyclic carbopalladation complex followed by C–H bond activation of the sp2 carbon in arenes. This domino reaction proceeds with good selectivity and provides good yields of the products. The requisite starting materials are synthesized by copper(I) iodide catalyzed A3-coupling reactions.

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Akkoç, Senem, Yetkin Gök, İlhan Özer İlhan und Veysel Kayser. „N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions“. Beilstein Journal of Organic Chemistry 12 (15.01.2016): 81–88. http://dx.doi.org/10.3762/bjoc.12.9.

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A series of novel benzimidazolium salts (1–4) and their pyridine enhanced precatalyst preparation stabilization and initiation (PEPPSI) themed palladium N-heterocyclic carbene complexes [PdCl2(NHC)(Py)] (5–8), where NHC = 1-(N-methylphthalimide)-3-alkylbenzimidazolin-2-ylidene and Py = 3-chloropyridine, were synthesized and characterized by means of 1H and 13C{1H} NMR, UV–vis (for 5–8), ESI-FTICR-MS (for 2, 4, 6–8) and FTIR spectroscopic methods and elemental analysis. The synthesized compounds were tested in Suzuki–Miyaura cross-coupling (for 1–8) and arylation (for 5–8) reactions. As catalysts, they demonstrated a highly efficient route for the formation of asymmetric biaryl compounds even though they were used in very low loading. For example, all compounds displayed good catalytic activity for the C–C bond formation of 4-tert-butylphenylboronic acid with 4-chlorotoluene.

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Arakawa, Yuki, Kenta Komatsu, Yuko Ishida, Takuma Shiba und Hideto Tsuji. „Thioether-Linked Liquid Crystal Trimers: Odd–Even Effects of Spacers and the Influence of Thioether Bonds on Phase Behavior“. Materials 15, Nr. 5 (24.02.2022): 1709. http://dx.doi.org/10.3390/ma15051709.

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We report the synthesis, phase-transition behavior, and mesophase structures of the first homologous series of thioether-linked liquid crystal (LC) trimers, 4,4′-bis[ω-(4-cyanobiphenyl-4′-ylthio)alkoxy]biphenyls (CBSnOBOnSCB with a wide range of spacer carbon numbers, n = 3–11). All CBSnOBOnSCB homologs exhibited LC phases. Interestingly, even-n and odd-n homologs showed monotropic layered smectic A (SmA) and pseudo-layered twist-bend nematic (NTB) phases, respectively, below a nematic (N) phase. This alternate formation, which depends on spacer chain parity, is attributed to different average molecular shapes, which are associated with the relative orientations of the biphenyl moieties: linear and bent shapes for even-n and odd-n homologs, respectively. In addition, X-ray diffraction analysis indicated a strong cybotactic N phase tendency, with a triply intercalated structure. The phase-transition behavior and LC phase structures of thioether-linked CBSnOBOnSCB were compared with those of the all-ether-linked classic LC trimers CBOnOBOnOCB. Overall, thioether linkages endowed CBSnOBOnSCB with a monotropic LC tendency and lowered phase-transition temperatures, compared to those of CBOnOBOnOCB, for the same n. This is attributed to enhanced flexibility and bending (less molecular anisotropy) of the molecules, caused by the greater bond flexibility and smaller inner bond angles of the C–S–C bonds, compared to those of the C–O–C bonds.

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Achar, Tapas Kumar, Anima Bose und Prasenjit Mal. „Mechanochemical synthesis of small organic molecules“. Beilstein Journal of Organic Chemistry 13 (11.09.2017): 1907–31. http://dx.doi.org/10.3762/bjoc.13.186.

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With the growing interest in renewable energy and global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C), carbon–nitrogen (C–N), carbon–oxygen (C–O), carbon–halogen (C–X), etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.

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RUSOP, M., T. SOGA und T. JIMBO. „RAMAN SCATTERING STUDIES ON THE STRUCTURAL PROPERTIES OF PULSED LASER DEPOSITED AMORPHOUS CARBON NITRIDE THIN FILMS“. Surface Review and Letters 12, Nr. 02 (April 2005): 173–84. http://dx.doi.org/10.1142/s0218625x05006913.

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Raman scattering analysis revealed that the structure of carbon (C) films prepared by pulsed laser deposition at room temperature is predominantly amorphous and the structure of amorphous C nitride ( a-CN x) films can be changed with varying substrate temperatures (ST) from 20 to 500°C. The deposited a-CN x films are composed of C–N , C≡N and C–O bonded materials and the C–N and C≡N bonds are increased with ST. We have found no other obvious peaks that can be distinguished in the range of 900 to 2300 cm-1 in which several peaks always appear in a-CN x films. The spectra were deconvoluted into Raman D and G peaks and the structural parameters were determined. The upward shifts of Raman G peak towards 1592 cm-1 show evidence of a progressive formation of crystallites in a-CN x films upon increase of ST, while the upward shifts of Raman D peak towards 1397 cm-1 have been related to the decrease of bond-angle disorder and sp 3 tetrahedral bonding in its structure. Raman FWHM and I D /I G also indicate that N incorporation with increase of ST caused an increase in the number and/or size of graphitic domains in the a-CN x films.

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Eisch, John J., Xian Shi und Jacek Lasota. „Carbon-Carbon Bond Formation by Reductive Coupling with Titanium(II) Chloride Bis(tetrahydrofuran)“. Zeitschrift für Naturforschung B 50, Nr. 3 (01.03.1995): 342–50. http://dx.doi.org/10.1515/znb-1995-0307.

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Titanium(II) bis(tetrahydrofuran) 1, generated by the treatm ent of TiCl4 in THF with two equivalents of n-butyllithium at -78 °C, has been found to form carbon-carbon bonds with a variety of organic substrates by reductive coupling. Diphenylacetylene is dimerized to exclusively (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene; benzyl bromide and 9-bromofluorene give their coupled products, bibenzyl and 9,9'-bifluorenyl, as do benzal chloride and benzotrichloride yield the 1,2-dichloro-1,2-diphenylethanes and 1,1,2,2-tetrachloro-1,2-diphenylethane, respectively. Styrene oxide and and cis-stilbene oxide undergo deoxygenation to styrene and fra/«-stilbene, while benzyl alcohol and benzopinacol are coupled to bibenzyl and to a mixture of tetraphenylethylene and 1,1,2,2-tetraphenylethane. Both aliphatic and aromatic ketones are smoothly reductively coupled to a mixture of pinacols and/or olefins in varying proportions. By a choice of experimental conditions either the pinacol or the olefin could be made the predom inant product in certain cases. The reaction has been carried out with heptanal, cyclohexanone, benzonitrile, benzaldehyde, furfural, acetophenone, benzophenone and 9-fluorenone. In a remarkable, multiple reductive coupling, benzoyl chloride is converted into 2,3,4,5-tetraphenylfuran in almost 50% yield. The stereochemical course of two such couplings, that of diphenylacetylene to yield exclusively (E,E)-1,2,3,4-tetraphenyl-l,3-butadiene and that of acetophenone to produce only racemic-2,3-diphenyl-2,3-butanediol, is interpreted to conclude that the couplings proceed via two electron transfer pathways (TET) involving titanium (IV) cyclic intermediates of the titanirene and the oxatitanacyclopropane type, respectively.

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Jones, Alan M., und Craig E. Banks. „The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions“. Beilstein Journal of Organic Chemistry 10 (18.12.2014): 3056–72. http://dx.doi.org/10.3762/bjoc.10.323.

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N-acyliminium ions are useful reactive synthetic intermediates in a variety of important carbon–carbon bond forming and cyclisation strategies in organic chemistry. The advent of an electrochemical anodic oxidation of unfunctionalised amides, more commonly known as the Shono oxidation, has provided a complementary route to the C–H activation of low reactivity intermediates. In this article, containing over 100 references, we highlight the development of the Shono-type oxidations from the original direct electrolysis methods, to the use of electroauxiliaries before arriving at indirect electrolysis methodologies. We also highlight new technologies and techniques applied to this area of electrosynthesis. We conclude with the use of this electrosynthetic approach to challenging syntheses of natural products and other complex structures for biological evaluation discussing recent technological developments in electroorganic techniques and future directions.

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Li, Jinlei, Guoliang Liu, Lijun Shi, Qi Xing und Fuwei Li. „Cobalt modified N-doped carbon nanotubes for catalytic CC bond formation via dehydrogenative coupling of benzyl alcohols and DMSO“. Green Chemistry 19, Nr. 24 (2017): 5782–88. http://dx.doi.org/10.1039/c7gc02335a.

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47

RUSOP, M., T. SOGA und T. JIMBO. „RAMAN SCATTERING STUDIES ON THE STRUCTURAL PROPERTIES OF PULSED LASER DEPOSITED AMORPHOUS CARBON NITRIDE THIN FILMS“. International Journal of Modern Physics B 19, Nr. 23 (20.09.2005): 3527–45. http://dx.doi.org/10.1142/s0217979205032309.

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Raman scattering analysis revealed that the structure of carbon films prepared by pulsed laser deposition (PLD) at room temperature is predominantly amorphous and the structure of amorphous carbon nitride ( a-CN x) thin films can be changed with varying substrate temperatures (ST) from 20°C to 500°C. The deposited a-CN x films are composed of C – N , C ≡ N and C – O bonded materials and the C – N and C ≡ N bonds are increased with ST. We have found that no other obvious peaks can be distinguished in the range 900–2300 cm-1 in which several peaks always appear in a-CN x films. The spectra were deconvoluted into Raman D and G peaks and the structural parameters are determined. The upward shifts of the Raman G peak towards 1592 cm-1 shows the evidence of a progressive formation of crystallites in a-CN x films upon increase of ST. While the upward shifts of the Raman D peak towards 1397 cm-1 have been related to the decrease of bond-angle disorder and sp3 tetrahedral bonding in its structure. Raman FWHM and I D /I G also indicate that N incorporation with increase of ST caused an increase in the number and/or size of graphitic domains in the a-CN x films.

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Bristow, Jonathan C., Matthew A. Addicoat und John D. Wallis. „O(−)⋯C interactions and bond formation in 1-naphtholate anions with peri-located electrophilic carbon centres“. CrystEngComm 21, Nr. 6 (2019): 1009–18. http://dx.doi.org/10.1039/c8ce01872c.

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n–π* interactions between naphtholate O anions and carbonyl groups are determined to be shorter than in corresponding naphthols by X-ray crystallography, and lead to cyclisations with long O–C bonds when the carbonyl group is replaced by a strongly electron deficient alkene.

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Mori, Makio, und Jack L. Koenig. „Solid-State C-13 NMR Studies of Vulcanized Elastomers XIII. TBBS Accelerated, Sulfur-Vulcanization of Carbon Black Filled Natural Rubber“. Rubber Chemistry and Technology 68, Nr. 4 (01.09.1995): 551–62. http://dx.doi.org/10.5254/1.3538756.

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Abstract Solid state C-13 NMR has been used to compare the chemistry of accelerated vulcanization of natural rubber using N-t-butyl-2-benzothiazole sulfenamide in the presence and absence of carbon black. The carbon black filler has an influence on the vulcanization chemistry in addition to its accepted role in reinforcment and stabilization. The basic network structure formation is modified to the extent that crosslink desulfurization from poly to monosulflde structures occurs earlier in the cure in the presence of carbon black. No main chain scission or double bond migration was detected.

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Fukumoto, Yoshiya, Masato Daijo und Naoto Chatani. „Rhenium(I)-catalyzed reaction of terminal alkynes with imines leading to allylamine derivatives“. Pure and Applied Chemistry 86, Nr. 3 (20.03.2014): 283–89. http://dx.doi.org/10.1515/pac-2014-5003.

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Abstract The rhenium-catalyzed reaction of terminal alkynes with imines gives N-alkylideneallylamine derivatives. A diphenylmethyl group as the substituent on the imine nitrogen gave the best result. Deuterium labeling experiments revealed that the regioselective addition of both the hydrogen and the N-alkylideneaminoalkyl group to the terminal alkynes also proceeded stereoselectively. While alkynes bearing primary and secondary alkyl-, vinyl-, and aryl groups were applicable to the catalytic reaction, tertiary alkyl- and silyl-substituted alkynes gave propargylamines. The C–C bond-forming step via the nucleophilic attack of the alkynyl β-carbon on the imine carbon leading to the formation of a vinylidene rhenium species appears to be involved in the catalytic cycle.

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