2039-82-9Relevant academic research and scientific papers
Kinetics and Mechanism of 1,4-Cycloaddition between Tetracyanoethylene and Styrenes. II. Effect of Para Substituents
Uosaki, Yasuhiro,Nakahara, Masaru,Osugi, Jiro
, p. 3681 - 3683 (1981)
The 1,4-cycloaddition of TCNE to p-methyl-, p-chloro-, and p-bromostyrenes by way of the EDA complex has been studied in chloroform at 25 deg C by the spectrophotometric method.The Hammett correlation obtained from the kinetic data provides -5.5 +/- 0.2 as the reaction constant ρ.The negative value is large in magnitude relative to other common 1,4-cycloadditions, suggesting some large partial charges in the rate-determining transition state.A linear correlation between the logarithmic forms of the reaction rate and the EDA-complex formation constant is in favor of the reaction scheme where the complex is on the pathway of the cycloaddition.
Permanently grafted icephobic nanocomposites with high abrasion resistance
Gao, Jing,Martin, Andrew,Yatvin, Jeremy,White, Evan,Locklin, Jason
, p. 11719 - 11728 (2016)
In this work, a series of copolymer/silica nanocomposites are investigated that exhibit excellent anti-icing behavior and can be covalently grafted to any substrate containing C-H bonds with high durability. The copolymers of interest consist of pendant benzophenone, hexafluorobutyl, and a variety of other comonomers that, under mild UV irradiation, can be covalently grafted on a variety of substrates and generate a densely cross-linked network of polymer and well-dispersed nanoparticles. The robustness of thin films was compared in a series of terpolymers with different acrylic comonomer content. Thin films prepared with tert-butyl ester side groups had less backbone chain scission and, therefore, a greater extent of cross-linking than films prepared with n-butyl ester side groups. The iso-butyl acrylate comonomer promotes photoreaction efficiency in terms of kinetic rate and network robustness, leading to films that can sustain high shear forces and abrasion. The anti-icing capability of the composite was investigated using the impact of supercooled water on different substrates. The composite maintains its icephobicity after modified Taber testing with multiple abrasion cycles using a 300 g load, which demonstrates excellent mechanical resistance. In addition, this study has led to rational design rules for copolymers that maximize permanent attachment of different surface functionalities in terms of both grafting density and reaction kinetics.
Dimsyl anion in the monoalkylation of solid-phase alkyl sulfones
Cheng, Wei-Chieh,Lin, Chu-Chung,Kurth, Mark J
, p. 2967 - 2970 (2002)
Polymer-bound α-sulfonyl monocarbanions can be generated very effectively with dimsyl anion. The highly efficient and convenient protocols presented here report the preparation of α,β-unsaturated ketones and vinylaryl compounds using dimsyl anion to achie
Selective reduction of alkynes to alkenes with hydrogen or formic acid catalyzed by cis,mer-[IrH2Cl(mtppms)3]
Hankó, Gy?rgy,Márton, Richárd,Udvardy, Antal,Purgel, Mihály,Kathó, ágnes,Joó, Ferenc,Papp, Gábor
, (2021)
In this work we have found, that the water-soluble cis,mer-[IrH2Cl(mtppms)3] (mtppms = monosulfonated triphenylphosphine Na-salt) was an excellent catalyst for reduction of terminal alkynes by hydrogen transfer from aqueous HCOOH/HCOONa mixtures. The conversions strongly depended on the pH of the reaction mixtures, and the highest rate of phenylacetylene transfer hydrogenation was observed at pH 3. The same dihydrido-Ir(III) complex actively catalyzed also the hydrogenation of terminal alkynes under mild conditions (T = 50 °C; P(H2) = 2–10 bar). Importantly, both the hydrogenation and hydrogen transfer reductions afforded exclusively the corresponding alkenes as products. Phenylacetylene and its substituted derivatives reacted smoothly, while benzylic and aliphatic alkynes were less reactive or did not react at all. It was also found, that an excess of the mtppms ligand inhibited the reaction. This was rationalized by formation of cisz-[IrH2(mtppms)4]+ which was also confirmed with multinuclear NMR spectroscopy. On the basis of the experimental results, a joint mechanism was suggested for both the hydrogenation and transfer hydrogenation pathways. The mechanism of hydrogenation and transfer hydrogenation of phenylacetylene was also studied by DFT calculations, which revealed several possibilities for protonation of a vinyl intermediate as the crucial step in formation of the styrene product.
Photoredox Catalyzed Sulfonylation of Multisubstituted Allenes with Ru(bpy)3Cl2 or Rhodamine B
Chen, Jingyun,Chen, Shufang,Jiang, Jun,Lu, Qianqian,Shi, Liyang,Xu, Zekun,Yimei, Zhao
supporting information, (2021/11/09)
A highly regio- and stereoselective sulfonylation of allenes was developed that provided direct access to α, β-substituted unsaturated sulfone. By means of visible-light photoredox catalysis, the free radicals produced by p-toluenesulfonic acid reacted with multisubstituted allenes to obtain Markovnikov-type vinyl sulfones with Ru(bpy)3Cl2 or Rhodamine B as photocatalyst. The yield of this reaction could reach up to 91%. A series of unsaturated sulfones would be used for further transformation to some valuable compounds.
Mild and efficient desulfurization of thiiranes with MoCl5/Zn system
Lee, Yeong Jin,Shin, Jeong Won,Yoo, Byung Woo
, (2021/11/10)
Desulfurization of a variety of thiiranes to alkenes occurs chemoselectively in high yields upon treatment with MoCl5/Zn system under mild conditions. The new methodology demonstrates high functional group tolerance toward chloro, bromo, fluoro, methoxy, ester, ether and keto groups.
Electrochemical Proton Reduction over Nickel Foam for Z-Stereoselective Semihydrogenation/deuteration of Functionalized Alkynes
Johansson, Magnus J.,Kaur, Gurpreet,Martín-Matute, Belén,Martínez-Pardo, Pablo,Valiente, Alejandro
, (2021/12/22)
Selective reduction strategies based on abundant-metal catalysts are very important in the production of chemicals. In this paper, a method for the electrochemical semihydrogenation and semideuteration of alkynes to form Z-alkenes was developed, using a simple nickel foam as catalyst and H3O+ or D3O+ as sources of hydrogen or deuterium. Good yields and excellent stereoselectivities (Z/E up to 20 : 1) were obtained under very mild reaction conditions. The reaction proceeded with terminal and nonterminal alkynes, and also with alkynes containing easily reducible functional groups, such as carbonyl groups, as well as aryl chlorides, bromides, and even iodides. The nickel-foam electrocatalyst could be recycled up to 14 times without any change in its catalytic properties.
Vinyl Thianthrenium Tetrafluoroborate: A Practical and Versatile Vinylating Reagent Made from Ethylene
Juliá, Fabio,Paulus, Fritz,Ritter, Tobias,Yan, Jiyao
supporting information, p. 12992 - 12998 (2021/09/03)
The use of vinyl electrophiles in synthesis has been hampered by the lack of access to a suitable reagent that is practical and of appropriate reactivity. In this work we introduce a vinyl thianthrenium salt as an effective vinylating reagent. The bench-stable, crystalline reagent can be readily prepared from ethylene gas at atmospheric pressure in one step and is broadly useful in the annulation chemistry of (hetero)cycles, N-vinylation of heterocyclic compounds, and palladium-catalyzed cross-coupling reactions. The structural features of the thianthrene core enable a distinct synthesis and reactivity profile, unprecedented for other vinyl sulfonium derivatives.
KO-t-Bu Catalyzed Thiolation of β-(Hetero)arylethyl Ethers via MeOH Elimination/hydrothiolation
Shigeno, Masanori,Shishido, Yoshiteru,Hayashi, Kazutoshi,Nozawa-Kumada, Kanako,Kondo, Yoshinori
supporting information, p. 3932 - 3935 (2021/08/24)
Herein, we describe a KO-t-Bu catalyzed thiolation of β-(hetero)arylethyl ethers through MeOH elimination to form (hetero)arylalkenes followed by anti-Markovnikov hydrothiolation to afford linear thioethers. The system works well with a variety of β-(hetero)arylethyl ethers, including electron-deficient, electron-neutral, electron-rich, and branched substrates and a range of aliphatic and aromatic thiols.
Method for simply, conveniently and efficiently synthesizing aromatic olefin derivative
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Paragraph 0035-0073, (2021/06/21)
The invention provides a method for simply, conveniently and efficiently synthesizing an aromatic olefin derivative, which comprises the following steps: by taking alpha-hydrogen-containing aromatic ketone as a raw material, carrying out reduction and deoxidation on ketone carbonyl under the combined action of trifluorosulfonic acid and hydrosilane to generate corresponding olefin. The method provided by the invention has excellent selectivity and simple operation process, uses a cheap catalytic reaction system, has good yield, and has huge application potential.
