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111.
To study the intramolecular Diels-Alder cycloadditon of 2H-chromen-2-one as a diene, a series of chiral N-allyl-N-benzylamides that contain a 2H-chromen-2-one moiety were designed for the synthesis of benzo[f]isoindol-1-ones via an intramolecular Diels-Alder and a subsequent retro-Diels-Alder cycloaddition with the expulsion of CO2. Both the yield (80%-89%) and absolute stereocontrol of the tandem reaction were high when an electron-withdrawing group was attached to the dienophile. The double bond in the styrene substructure remained in the products could be further derivatized by dihydroxylation. 相似文献
112.
Hui Ding Jin-Long Qi Yu-Jie Gao Ru-Ru Chen She-Jiang Liu Xu Han 《Chemical Papers》2016,70(10):1380-1388
As a novel process intensification technology, microwave-assisted continuous reaction distillation (MRD) was proposed for the esterification reaction and separation of ethyl acetate (EtOAc). The effects of reflux ratio, mole ratio of acetic acid (HOAc) to ethanol (EtOH), reboiler duty, microwave power on EtOH conversions, EtOAc purity and mass ratio of distillate to feed (D/F) were explored. In comparison with conventional heating, the experimental results revealed that the EtOAc purity in the distillate under microwave conditions (MC) was improved. Computer simulations for conventional and MRD systems were performed using the Aspen Plus non-equilibrium stage model to substantiate the experimental results. The model predictions are in good agreement with the experimental data, revealing the accuracy and reliability of the non-equilibrium model. This new MRD process can be an effective and productive method of ester production. 相似文献
113.
A method to obtain ground state electroluminescence from 1.3μm emitting InAs/GaAs quantum dots grown by molecular beam epitaxy 下载免费PDF全文
1.3μm emitting InAs/GaAs quantum dots(QDs) have been grown by molecular beam epitaxy and QD light emitting diodes(LEDs) have been fabricated.In the electroluminescence spectra of QD LEDs,two clear peaks corresponding to the ground state emission and the excited state emission are observed.It was found that the ground state emission could be achieved by increasing the number of QDs contained in the active region because of the state filling effect.This work demonstrates a way to control and tune the emitting wavelength of QD LEDs and lasers. 相似文献
114.
2-噻吩乙酸在三种不同树脂上的吸附热力学和动力学研究 总被引:12,自引:0,他引:12
通过静态吸附实验,研究了XAD-4,NDA-100和ND-90吸附树脂对水溶液中2-噻吩乙酸的吸附热力学及动力学特性,结果表明,2-噻吩乙酸在XAD-4树脂上是单层吸附,符合Langmuir等温吸附方程,吸附过程符合准一级动力学吸附方程.2-噻吩乙酸在NDA-100和ND-90树脂上的吸附也能用Langmuir等温吸附方程表示,但并不只是单层吸附,而主要是由毛细管凝聚和微孔填充作用造成的吸附,吸附过程可分为大孔和中孔区的吸附以及微孔区的吸附两个阶段,两个阶段都符合准一级动力学吸附方程. 相似文献
115.
A simple and convenient tandem reaction of α-ketoesters with primary or secondary aromatic amines for the synthesis of polysubstituted 1,2-dihydroquinolines has been developed. The catalytic system (fluorous hydrazine-1,2-bis(carbothioate)/NCS) of the reaction has the advantages of operational simplicity, high efficiency, as well as easy recyclability. 相似文献
116.
Jin-Long Zhang Liang-An Chen Rui-Bin Xu Chuan-Fei Wang Yuan-Ping Ruan Ai-E Wang Pei-Qiang Huang 《Tetrahedron: Asymmetry》2013,24(8):492-498
Novel chiral imidazo[1,5-a]tetrahydroquinoline N-heterocyclic carbenes derived from β-pinene have been developed. The preliminary studies with both the in situ generated and preformed copper–carbene complexes have shown these chiral NHCs are efficient and selective ligands in the Cu-catalyzed asymmetric conjugate borylation of α,β-unsaturated esters. 相似文献
117.
Weiwei Zou Jin-Long Zhang Feng Chen Masakazu Anpo Dan-Nong He 《Research on Chemical Intermediates》2009,35(6-7):717-726
The surface of titanium dioxide nanoparticles has been chemically modified with toluene 2,4-di-isocyanate (TDI). The modified titanium dioxide can efficiently absorb visible irradiation. The samples were characterized by means of wide-angle X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), diffuse reflectance UV–Vis spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The as-prepared photocatalyst exhibited good photostability and photocatalytic performance in the degradation of organic compounds. For model organic pollutants, modified titanium dioxide had excellent visible-light photocatalytic performance and the surface chemistry linkage product had high photostability. 相似文献
118.
Xiao-Li Yuan Jin-Long Zhang Masakazu Anpo Dan-Nong He 《Research on Chemical Intermediates》2010,36(1):83-93
Fe3+ doped mesoporous TiO2 with ordered mesoporous structure were successfully prepared by the solvent evaporation-induced self-assembly process using
P123 as soft template. The properties and structure of Fe3+ doped mesoporous TiO2 were characterized by means of XRD, EPR, BET, TEM, and UV–vis absorption spectra. The characteristic results clearly show
that the amount of Fe3+ dopant affects the mesoporous structure as well as the visible light absorption of the catalysts. The photocatalytic activity
of the prepared mesoporous TiO2 was evaluated from an analysis of the photodegradation of methyl orange under visible light irradiation. The results indicate
that the sample of 0.50%Fe–MTiO2 exhibits the highest visible light photocatalytic activity compared with other catalysts. 相似文献
119.
Han JM Pan JL Lei T Liu C Pei J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13850-13861
A family of macrocycles with oligo(ethylene glycol) chains, 4O, 5O, and 6O, was developed to construct a series of new incorporated macrocycles through dynamic covalent chemistry. These flexible macrocycles exhibited excellent "self-sorting" abilities with diamine compounds, which depended on the "induced-fit" rule. For instance, the host macrocycles underwent conformational modulation to accommodate the diamine guests, affording [1+1] intramolecular addition compounds regardless of the flexibility of the diamine. These macrocycles folded themselves to fit various diamines with different chain length through modulation of the flexible polyether chain, and afforded intramolecular condensation products. However, if the chain of the diamine was too long and rigid, oligomers or polymers were obtained from the mixture of the macromolecule and the diamine. All results demonstrated that inclusion compounds involving conformationally suitable aromatic diamines were thermodynamically favorable candidates in the mixture due to the restriction of the macrocycle size. Furthermore, kinetic and thermodynamic studies of self-sorting behaviors of both mixed 4O-5O and 4O-6O systems were investigated in detail. Finally, theoretical calculations were also employed to further understand such self-sorting behavior, and indicated that the large enthalpy change of H(2)NArArNH(2)@4O is the driving force for the sorting behavior. Our system may provide a model to further understand the principle of biomolecules with high specificity due only to their conformational self-adjusting ability. 相似文献
120.
We experimentally investigate the coherence of a single mode InAlGaAs/InP cylindrical microlaser with two output waveguides. For a cylindrical microlaser with a radius of 15 μm and two 2 μm-wide output waveguides, single mode operation with a side mode suppression ratio of 30 dB is realized, and a far-field interferometric pattern similar to a Young's interferometer is observed. The results indicate that the microlasers with two output waveguides can be used as the light source for an optical sensor by monitoring the phase change of the output emission from one port versus that of the other port. 相似文献