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Shi X.-Y.,Key Laboratory for Macromolecular Science of Shaanxi Province | Han W.-J.,Key Laboratory for Macromolecular Science of Shaanxi Province | Li C.-J.,McGill University
Chemical Record | Year: 2016

The direct addition of Csp2–H bonds onto polar C=C, C=O, and C=N bonds is both synthetically and mechanistically important, because using aromatic C–H substrates in place of organometallic reagents provides a more direct and atom-economical alternative to many important compounds without the pre-generation of organometallic compounds from stoichiometric halides and the unavoidable generation of stoichiometric metal halide waste. In this account, we summarize our contributions to the transition-metal-catalyzed addition of aromatic C–H bonds to polar C=C, C=O, and C=N bonds via directing-group-assisted regiospecific reactions. These synthetic methods provide efficient access to benzylic alcohols, alkylbenzenes, 3-substituted phthalides, N-substituted phthalimides, N-aryl benzamides, and indene derivatives from commercially available reagents. It is worth noting that valuable heterocycles such as 3-substituted phthalides and N-substituted phthalimides can be obtained in one step by this approach. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Shi X.,Shaanxi Normal University | Shi X.,Key Laboratory for Macromolecular Science of Shaanxi Province | Han X.,Shaanxi Normal University | Han X.,Key Laboratory for Macromolecular Science of Shaanxi Province | And 11 more authors.
Journal of Molecular Catalysis A: Chemical | Year: 2011

Peroxotungstates held in a series of different supported ionic liquid brush catalysts were synthesized and characterized. Their catalytic performance towards the selective oxidation of sulfides with aqueous hydrogen peroxide was investigated under mild conditions. We found that the catalytic activities of the different catalysts depend on the number of supported ionic liquid layers and N-end-capped alkyl group on the imidazole ring. The highest yield of methyl phenyl sulfoxide was obtained using the BisILs-C8H17-W2 catalyst under optimum conditions. The sulfides were selectively oxidized to sulfoxides in high yields with trace sulfones detected by GC upon using 1.1 equivalents of H2O2. At 2.5 equivalents of H 2O2 the sulfones were found to be the main products. It is noteworthy that the catalyst resulted in high chemoselectivity towards sulfur groups with unsaturated double bonds even though excess hydrogen peroxide was used in addition to exhibiting high catalytic activity. There was no apparent loss of catalytic efficiency until the 8th cycle. © 2011 Elsevier B.V. All rights reserved. Source


Chao X.,Key Laboratory for Macromolecular Science of Shaanxi Province | Chao X.,Shaanxi Normal University | Yang Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Yang Z.,Shaanxi Normal University | And 4 more authors.
Journal of Alloys and Compounds | Year: 2011

In this work, we report on the Pb(Mg1/3Nb2/3)O 3-Pb(Zn1/3Nb2/3)O3-Pb(Zr 0.52Ti0.48)O3 (PMN-PZN-PZT) ceramics with Ba(W0.5Cu0.5)O3 as the sintering aid that was manufactured in order to develop the low-temperature sintering materials for piezoelectric device applications. The phase transition, microstructure, dielectric, piezoelectric properties, and the temperature stability of the ceramics were investigated. The results showed that the addition of Ba(W 0.5Cu0.5)O3 significantly improved the sintering temperature of PMN-PZN-PZT ceramics and could lower the sintering temperature from 1005 to 920 °C. Besides, the obtained Ba(W 0.5Cu0.5)O3-doped ceramics sintered at 920 °C have optimized electrical properties, which are listed as follows: (Kp = 0.63, Qm = 1415 and d33 = 351 pC/N), and high depolarization temperature above 320 °C. These results indicated that this material was a promising candidate for high-power multilayer piezoelectric device applications. © 2010 Elsevier B.V. All rights reserved. Source


Yang Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Yang Z.,Shaanxi Normal University | Gu R.,Key Laboratory for Macromolecular Science of Shaanxi Province | Gu R.,Shaanxi Normal University | And 4 more authors.
Journal of Alloys and Compounds | Year: 2010

Ta5+ doped strontium barium niobate (SBN) ceramics were synthesized by conventional oxide-mixed method. The phase structure, microstructure and dielectric properties of the ceramics with different Ta 5+ contents and sintering temperatures were investigated. The X-ray diffraction patterns show that pure tungsten bronze structure can be obtained in all the ceramics. The ceramics with high relative density and a uniform and fine-grained microstructure could be obtained at 1430 °C. The grain size of Sr0.53Ba0.47Nb2-xTaxO6 decreased with increasing the Ta5+ content. The relaxor behavior observed in SBNT ceramics should be attributed to a cationic disorder induced by B-site substitutions, which was proved by linear fitting of the modified Curie-Weiss law. All samples are proved to be relaxor ferroelectric. It is also found that Curie temperature Tc and maximum dielectric constant εm both decrease with increasing Ta5+ content. © 2010 Elsevier B.V. All rights reserved. Source


Chen Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Chen Z.,Shaanxi Normal University | Li Y.,Key Laboratory for Macromolecular Science of Shaanxi Province | Li Y.,Shaanxi Normal University | And 5 more authors.
Chemical Research in Chinese Universities | Year: 2014

An efficient method for the bromoamidation of β,β-dicyanostyrene derivatives with N-bromoacetamide (NBA) was developed. This protocol provides a convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines in excellent yields(up to 99%) at room temperature in the presence of anhydrous K3PO4 as a catalyst without the protection of the inert gaseous in CH2Cl2. A total of 11 examples were investigated and all the products showed the regionspecific feature. Based on the observation of different activities for the different substrates involving the electron-rich or electron-deficient β,β-dicyanostyrenes, a possible Michael addition mechanism was proposed. © 2014 Jilin University, The Editorial Department of Chemical Research in Chinese Universities and Springer-Verlag GmbH. Source

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