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911.
912.
913.
Zhigang Xue Rinaldo Poli 《Journal of polymer science. Part A, Polymer chemistry》2013,51(16):3494-3504
The radical polymerization of vinyl acetate (VAc) is moderated by iron(II) acetylacetonate (Fe(acac)2) by the organometallic route (OMRP), as well as by degenerative transfer polymerization (DTP) when in the presence of excess radicals, through the formation of thermally labile organometallic FeIII dormant species. The poly(vinyl acetate) (PVAc)‐FeIII(acac)2 dormant species has been isolated in the form of an oligomer and characterized by 1H NMR, EPR, and IR methods, and then used as a single‐component initiator for the OMRP of VAc. The degree of polymerization of this isolated oligomeric species demonstrates the limited ability of Fe(acac)2, relative to the Co(acac)2 congener, to rapidly trap the growing PVAc radical chain. Control under OMRP conditions is improved by the presence of Lewis bases, especially PMe2Ph. On the other hand, iron(II) phthalocyanine inhibits the radical polymerization of VAc completely. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3494–3504 相似文献
914.
Zhiyong Gong Qingwen Liu Pengchong Xue Kechang Li Zhiguang Song Zaiqun Liu Yinghua Jin 《应用有机金属化学》2012,26(3):121-129
Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et2Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
915.
Shu Yin Peilin Zhnag Bin Liu Xiangwen Liu Tsugio Sato Dongfeng Xue Soo Wohn Lee 《Research on Chemical Intermediates》2010,36(1):69-75
Nitrogen-doped titania (TiO2−xNy) nanoparticles with monoclinic phase were successfully prepared by a microwave-assisted hydrothermal process. The obtained
TiO2−xNy powders showed high specific surface area, fine particle size, and excellent photocatalytic ability for the oxidative destruction
of nitrogen monoxide under irradiation of monochromatic LED light with various wavelengths. 相似文献
916.
Yuexing Zhang Dongdong Qi Xue Cai Jianzhuang Jiang 《International journal of quantum chemistry》2010,110(8):1559-1564
The nature of the near‐IR band in the electronic absorption spectra of bis(tetrapyrrole) rare earth(III) complexes Y(Pc)2 (1), La(Pc)2 (2), Y(Pc)(Por) (3), Y(Pc)[Pc(α‐OCH3)4] (4), Y(Pc)[Pc(α‐OCH3)8] (5), and Y(Pc)[Pc(β‐OCH3)8] (6) was studied on the basis of time‐dependent density functional theory (TD‐DFT) calculations. The electronic dipole moment along the z‐axis in the electronic transition of the near‐IR band in all the studied neutral bis(tetrapyrrole) yttrium(III) and lanthanum(III) double‐deckers is well explained on the basis of the composition analysis of the orbitals involved. The electronic transition in the near‐IR band causes the reversion of the orbital orientation of one tetrapyrrole ring in both homoleptic and heteroleptic bis(tetrapyrrole) rare earth complexes and induces electron transfer from the tetrapyrrole ring with lower orbital energy to the other ring in the heteroleptic bis(tetrapyrrole) rare earth(III) complexes. The near‐IR band can work as an ideal characteristic absorption band to reflect the π–π interaction between the two tetrapyrrole rings in bis(tetrapyrrole) rare earth(III) double‐decker complexes because of its peculiar electronic transition nature. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
917.
In the paper, a cross‐flow fan in refrigerant operating condition is systematically simulated using user‐defined functions. Three‐dimensional simulations are acquired with Navier–Stokes equations coupled with k–ε turbulence model, and internal flow characteristics of an indoor split‐type air conditioner are obtained, which is mainly composed of cross‐flow fan and heat exchanger. It has systematically been simulated in the isothermal flow condition that the performance of cross‐flow fan may be reduced easily with dry or humid air, and in the refrigerant operating condition in which user‐defined functions are applied to the humid air, considered as a mixture of dry air and vapor. A density‐modulated function is adopted to deal with the condensation of the vapor at the heat‐transfer region approximately. The results show flow mechanism of the two gas‐phase flow, including phase‐vary process. The distribution of the parameters is not uniform at the inlet of the machine, the intensity and position of pressure and velocity vary along the axial direction of the fan, the distribution of vapor volume fraction and turbulent intensity in heat‐transfer region is obtained, and the external characteristic data of the indoor machine are obtained and analyzed. Compared with the experimental data, the calculated characteristic curves and designed parameters are on target. © British Crown Copyright 2010/MOD. Reproduced with permission. Published by John Wiley & Sons, Ltd. 相似文献
918.
Yiwei Zhang Yuming Zhou Lihui Wan Mengwei Xue Yongzheng Duan Xuan Liu .School of Chemistry Chemical Engineering Southeast University Nanjing Jiangsu China .Biochemical Environmental Engineering College Nanjing Xiaozhuang University Nanjing 《天然气化学杂志》2011,20(6):639-646
Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction. 相似文献
919.
Weimin Xue 《代数通讯》2013,41(5):2633-2638
920.
Dan Zheng Li Han Yi Jiang Yan‐Ru Cao Jiang Liu Xiu Chen Yi‐Qing Li Xue‐Shi Huang 《Magnetic resonance in chemistry : MRC》2013,51(3):188-191
Four new prenylindole derivatives, (R)‐6‐(2,3‐dihydroxy‐3‐methylbutyl)indole (1), (R)‐6‐(2,3‐dihydroxy‐3‐methylbutyl)indolin‐2‐one (2), and an unseparated mixture of (Z)‐6‐(4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl)indolin‐2‐one (3a) and (E)‐6‐(4‐hydroxy‐3‐methylbut‐2‐en‐1‐yl)indolin‐2‐one (3b) with a ratio of 3 : 2, were isolated from the culture broth of a streptomycete isolated from Ailuropoda melanoleuca feces. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopic techniques. The absolute configuration of 1 was determined by Mosher's method. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献