Key Laboratory for Macromolecular Science of Shaanxi Province

Fengcheng, China

Key Laboratory for Macromolecular Science of Shaanxi Province

Fengcheng, China

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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.


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.


Chen Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Chen Z.,Shaanxi Normal University | Xia W.,Key Laboratory for Macromolecular Science of Shaanxi Province | Xia W.,Shaanxi Normal University | And 8 more authors.
Journal of the Chinese Chemical Society | Year: 2016

The aminobromination of β,β-dicyanostyrene derivetives with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) has been systematic studied. The reaction afforded the vicinal haloamino products in good to excellent yields at room temperature (the highest yield was up to 94 %), and the full regiospecificity of all products were achieved catalyzed by NaHCO3 in CH3CN. A possible pathway involving a Michael Addition reaction for this aminobromination was proposed. A new method for the NaHCO3-catalyzed aminobromination of β,β-dicyanostyrene derivatives with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) has been developed. The reaction afforded the vicinal haloamino products in good to excellent yields at room temperature(the highest yield was up to 94 %). A possible pathway involving a Michael addition fashion for this aminobromination was proposed. © 2016 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany.


Chen Z.,Shaanxi Normal University | Chen Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Wei J.,Shaanxi Normal University | Wei J.,Key Laboratory for Macromolecular Science of Shaanxi Province | And 8 more authors.
Chinese Journal of Chemistry | Year: 2011

(+)-Tartaric acid-catalyzed aminobromination of α,β-unsaturated ketones, α,β-unsaturated esters and simple olefins utilizing TsNH2/NBS as the nitrogen/halogen sources at room temperature without protection of inert gases achieved good yields (up to 92% yield) of vicinal haloamino products with excellent regio- and stereoselectivity, even just 10% of (+)-tartaric acid was used as catalyst. The regio- and stereochemistry was unambiguously confirmed by X-ray structural analysis of products 2b and 12c. The electron-rich and deficient olefins show significant differences in activity to the aminobromination reaction and give the opposite regioselectivities. The 21 cases have been investigated which indicated that our protocol has the advantage of a large scope of olefins. Additionally, tartaric acid as catalyst has the advantage of avoiding any hazardous metals retained in products. © 2011 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


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.


Li W.,Key Laboratory for Macromolecular Science of Shaanxi Province | Li W.,Shaanxi Normal University | Chen Z.,Key Laboratory for Macromolecular Science of Shaanxi Province | Chen Z.,Shaanxi Normal University | And 6 more authors.
Chinese Journal of Chemistry | Year: 2012

An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH 3CN catalyzed by NaOAc (10 mol%) is developed. This protocol provides convenient process to convert β,β-dicyanostyrene derivatives into the vicinal haloamines with full regiospecificity and high stereoselectivety in the ice-water bath in air. The reaction is high efficient in yielding the corresponding aminobrominated products in excellent yields (up to 95%) under these conditions. The outcome indicated that the reaction has an electrophilic addition feature. 12 Eexamples of β,β-dicyanostyrene derivatives have been investigated. An easy and efficient method for the aminobromination of β,β-dicyanostyrene derivatives with NBS as the aminobrominating reagent in CH 3CN catalyzed by NaOAc (10 mol%) is developed. The reaction is high efficient in yielding the corresponding aminobrominated products in excellent yields (up to 95%). Copyright © 2012 SIOC, CAS, Shanghai & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Shi X.-Y.,Shaanxi Normal University | Shi X.-Y.,Key Laboratory for Macromolecular Science of Shaanxi Province | Sun M.,Shaanxi Normal University | Sun M.,Key Laboratory for Macromolecular Science of Shaanxi Province | And 8 more authors.
Applied Organometallic Chemistry | Year: 2015

In the reported extraction and catalytic oxidative desulfurization (ECODS) process, the highest sulfur removal can reach 100% for both benzothiophene and dibenzothiophene. The catalyst can be easily recovered and recycled five times without significant decrease in activity. Methanol as solvent does not affect the quality of the oil. This ECODS process has no apparent scale-up effect and contamination of the fuel by the metal catalyst can be avoided.A novel, efficient and reusable heterogeneous catalytic assembly of peroxophosphotungstate held in an ionic liquid brush was synthesized and an extraction and catalytic oxidative desulfurization (ECODS) procedure was developed for a model oil of benzothiophene (BT) and dibenzothiophene (DBT) using 30wt% hydrogen peroxide as terminal oxidant and methanol as solvent under mild conditions. Several factors that affect sulfur removal were investigated in detail. The highest sulfur removal can reach 100% for BT in 7h at 70°C when the molar ratio of H2O2, S and catalyst is 10:1:0.025. The sulfur removal for DBT can also reach 100% in 4h at 50°C with the same molar ratio of H2O2, S and catalyst. The experimental results demonstrate that this ECODS process has no apparent scale-up effect. The catalyst can be easily recovered (via simple filtration) and recycled five times without a significant decrease in activity. © 2015 John Wiley & Sons, Ltd.


Chen Z.-G.,Shaanxi Normal University | Chen Z.-G.,Key Laboratory for Macromolecular Science of Shaanxi Province | Wang Y.,Shaanxi Normal University | Wang Y.,Key Laboratory for Macromolecular Science of Shaanxi Province | And 6 more authors.
Journal of Organic Chemistry | Year: 2010

"Chemical Equation Presented" A very simple, efficient, and regiospecific protocol for aminobromination of a wide scope of β-nitrostyrene derivatives with N-bromoacetamide (NBA) as nitrogen/ bromine sources has been developed by using K3PO4 as catalyst. The reaction proceeded smoothly and cleanly to give the bromoamines in good to excellent yields (78-99%) within 24 h in CH2Cl2 at room temperature without protection of inert gases. A possible mechanism involving a nucleophilic conjugate addition was proposed. © 2010 American Chemical Society.


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.


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.

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