- High-capacity organic cathode active materials of 2,2′-bis-p-benzoquinone derivatives for rechargeable batteries
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Rechargeable batteries using organic cathode materials are expected to afford high mass energy densities since these materials can undergo multiple electron redox reactions per molecule. Although the batteries using benzoquinone (BQ) derivatives as organic cathode active materials exhibited high theoretical capacity, their practical capacities and cycle retention were far from satisfactory. To overcome these problems, dimeric BQ derivatives based on the 2,2′-bis-p-benzoquinone (BBQ) framework were synthesized, and the charge-discharge behaviour of the prepared cells using BBQs as the cathode active materials was investigated. BBQ-based cells exhibited excellent performance compared to those based on BQ monomers. For example, the BBQ cell afforded a high initial capacity of 358 A h kg-1 (more than twice that of current lithium-ion batteries that use LiCoO2 as the cathode active material) and a high cycle retention of 198 A h kg-1 at 50 cycles. Electrochemical measurements and density functional theory (DFT) calculations indicated that three electron-redox reactions generally occur in BBQ derivatives, although (OMe)2-BBQ appeared to undergo a four-electron redox reaction.
- Yokoji, Takato,Kameyama, Yuki,Maruyama, Norihiko,Matsubara, Hiroshi
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- Direct Synthesis of Hydroquinones from Quinones through Sequential and Continuous-Flow Hydrogenation-Derivatization Using Heterogeneous Au–Pt Nanoparticles as Catalysts
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Pt–Au bimetallic nanoparticle catalysts immobilized on dimethyl polysilane (Pt–Au/(DMPSi-Al2O3)) have been developed for selective hydrogenation of quinones to hydroquinones. High reactivity, selectivity, and robustness of the catalysts were confirmed under continuous-flow conditions. Various direct derivatizations of quinones, such as methylation, acetylation, trifluoromethanesulfonylation, methacrylation, and benzoylation were successfully performed under sequential and continuous-flow conditions to afford the desired products in good to excellent yields. Especially, air-sensitive hydroquinones, such as anthrahydroquinones and naphthohydroquinones, could be successfully generated and derivatized under closed sequential and continuous-flow conditions without decomposition.
- Miyamura, Hiroyuki,Tobita, Fumiya,Suzuki, Aya,Kobayashi, Shū
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p. 9220 - 9224
(2019/06/13)
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- Highly selective conversion of guaiacol to: Tert -butylphenols in supercritical ethanol over a H2WO4 catalyst
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The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Br?nsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
- Mai, Fuhang,Cui, Kai,Wen, Zhe,Wu, Kai,Yan, Fei,Chen, Mengmeng,Chen, Hong,Li, Yongdan
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p. 2764 - 2771
(2019/02/01)
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- Synthesis and testing of chromogenic phenoxazinone substrates for β-alanyl aminopeptidase
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Novel 7-N-(β-alanyl)aminophenoxazin-3-one salts 27a-d have been synthesized and tested as chromogenic substrates for β-alanyl aminopeptidase, which is present in Pseudomonas aeruginosa, the most common respiratory pathogen in patients with cystic fibrosis. The biological results show that 7-N-(β-alanyl)amino-1-pentylphenoxazin-3-one trifluoroacetate salt 27a is a chromogenic substrate for this bacterium, with a low degree of diffusion in nutrient media for growing bacterial cultures and a bright red colour, making it easily distinguishable from the agar background. This journal is The Royal Society of Chemistry.
- Zaytsev, Andrey V.,Anderson, Rosaleen J.,Bedernjak, Alexandre,Groundwater, Paul W.,Huang, Yongxue,Perry, John D.,Orenga, Sylvain,Roger-Dalbert, Celine,James, Arthur
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p. XX682-692
(2008/09/17)
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- Synthesis of quinoline-2-thiones via tandem indium(III)-promoted friedel-crafts alkenylation-cyclization of 2-alkynylphenyl isothiocyanates
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A new approach to the synthesis of 4-aryl- or 4-arylthioquinoline-2-thiones via indium(III) reagent-mediated tandem Friedel-Crafts alkenylation-cyclization of 2-alkynylphenyl isothiocyanates is described.
- Otani, Takashi,Kunimatsu, Shinichi,Nihei, Hiroshi,Abe, Yuko,Saito, Takao
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p. 5513 - 5516
(2008/09/17)
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- New chiral diamide ligands containing redox-active hydroquinone groups. Synthesis and results in the palladium(II)-catalyzed 1,4-diacetoxylation of 1,3-dienes
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Chiral ligands 8-11, 22 and 23 were synthesized from different chiral diamines as a new class of ligands for the Pd(II)-catalyzed 1,4-diacetoxylation of 1,3-dienes. The synthesis from the diamines and protected benzoic acids was performed in a few simple steps and gave the ligands in high overall yields. The hydroquinone groups present in the ligands are in situ oxidized to benzoquinone to give the active ligands. Application of these ligands in the 1,4-diacetoxylation reaction afforded the oxidation product with high regio- and diastereoselectivity and an enantiomeric excess up to 42% was obtained. Possible coordination modes of the metal to the ligand are discussed, and experiments were made to investigate the coordination by varying the reaction conditions or making changes to the ligands.
- Verboom, Renzo C.,Plietker, Bernd J.,B?ckvall, Jan-E.
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p. 508 - 517
(2007/10/03)
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- Rhenium complexes-catalyzed alkylation of arenes with alkyl halides
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Rhenium complexes have been shown to catalyze the alkylation of arenes with alkyl halides. When arenes were reacted with an alkyl chloride in the presence of a catalytic amount of rhenium complexes, such as bromopentacarbonylrhenium(I) [ReBr(CO)5], tricarbonylcyclopentadienylrhenium(I) [Re(C5H5)(CO)3] and decacarbonyldirhenium [Re2(CO)10], alkylation of the arenes proceeded under mild conditions to give a mixture of mono- and dialkyl substituted arenes in moderate-to-good yields.
- Nishiyama,Kakushou,Sonoda
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p. 2779 - 2782
(2007/10/03)
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- Reaction of aromatic radical cations with RuCl3·3H2O
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Interactions of RuCl3·3H2O with radical cations of aromatic ethers, 1,4-di-tert-butyl-2,5-dimethoxybenzene, 3,5-di-tert-butyl-1,2-dimethoxybenzene and 2-tert-butyl-1,4-dimethoxybenzene, and with aromatic amines, 2,4,6-tri-tert-butylaniline and N,N,N′,N′-tetramethyl-1,4-phenylenediamine, were observed by voltammetry. ESR and UV spectroscopies were used for the study of the the first two ethers. The effect of RuCl3·3H2O was also examined by controlled potential electrolysis.
- Michman, Michael,Oron, Miriam,Schaefer, Hans J.
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p. 924 - 940
(2007/10/03)
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