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941.
Cobalt‐based metal coordination polymers with 4,4′‐bipyridinyl groups: highly efficient catalysis for one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions
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Jin‐Hua Wang Gui‐Mei Tang Shi‐Chen Yan Yong‐Tao Wang Shi‐Jie Zhan E Zhang Yu Sun Yuan Jiang Yue‐Zhi Cui 《应用有机金属化学》2016,30(12):1009-1021
Three new metal coordination complexes, namely [Co(BPY)2(H2O)2](BPY)(BS)2(H2O)4 ( 1 ), [Co(BPY)2(H2O)4](ABS)2(H2O)2 ( 2 ) and [Co(BPY)(H2O)4](MBS)2 ( 3 ) (BPY = 4,4′‐bipyridine, BS = phenylsulfonic acid, ABS = p‐aminobenzenesulfonic acid, MBS = p‐methylbenzenesulfonic acid), were obtained under hydrothermal conditions. Complexes 1 , 2 , 3 were structurally characterized using single‐crystal X‐ray diffraction and infrared spectroscopy. All of them display low‐dimensional motifs: complex 1 displays a two‐dimensional structure; and complexes 2 and 3 exhibit a one‐dimensional tape structure. Through strong intermolecular hydrogen bonding interactions and weak packing interactions, all of them further stack to generate a three‐dimensional supramolecular architecture. Catalysts 1 , 2 , 3 were involved in the green synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones under solvent‐free conditions through Biginelli reactions. The corresponding catalytic product was obtained in quantitative yields (99%) under eco‐friendly synthesis conditions for the variety of reactions. Catalysts 1 , 2 , 3 exhibit excellent efficiency for the desired product, and their catalytic performance shows the following order: 2 > 1 ≈ 3 , which can be ascribed to the hydrophobic interactions of different phenylsulfonate groups. The catalytic performance for the Biginelli reaction is not only dependent on the selected solvents, but also inversely proportional to the polarities of the solvents. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
942.
943.
In this paper, by using a special matrix factorization, a symbolic computational algorithm is developed to solve the cyclic penta-diagonal linear system. The algorithm is suitable for implementation using Computer Algebra Systems (CASs) such as MATLAB, MATHEMATICA and MAPLE. In addition, an efficient way of evaluating the determinant of a cyclic penta-diagonal matrix is also discussed. Two numerical examples are given for the purpose of illustration. 相似文献
944.
A nucleophilic substitution reaction of an α‐ferrocenyl alcohol with various amines, indoles and thiols was successfully developed by using a catalytic amount of Bi(NO3)3.5H2O at room temperature without the aid of phase transfer catalyst. The reactions proceeded in aqueous media, leading to the formation of new C=C, C=N and C=S bonds bearing ferrocenyl substituent with high efficiency. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
945.
Phase separation dynamics of a poly(vinyl methyl ether)/polystyrene (PVME/PS) blend studied by ultrafast differential scanning calorimetry
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Shaochuan Luo Lai Wei Jing Jiang Ye Sha Gi Xue Xiaoliang Wang Dongshan Zhou 《Journal of Polymer Science.Polymer Physics》2017,55(18):1357-1364
In this work, ultrafast differential scanning calorimetry (UFDSC) is used to study the dynamics of phase separation. Taking poly(vinyl methyl ether)/polystyrene (PVME/PS) blend as the example, we firstly obtained the phase diagram that has lower critical solution temperature (LCST), together with the glass transition temperature (Tg) of the homogeneous blend with different composition. Then, the dynamics of the phase separation of the PVME/PS blend with a mass ratio of 7:3 was studied in the time range from milliseconds to hours, by the virtue of small time and spatial resolution that UFDSC offers. The time dependence of the glass transition temperature (Tg) of PVME‐rich phase, shows a distinct change when the annealing temperature (Ta) changes from below to above 385 K. This corresponds to the transition from the nucleation and growth (NG) mechanism to the spinodal decomposition (SD) mechanism, as was verified by morphological and rheometric investigations. For the SD mechanism, the temperature‐dependent composition evolution in PVME‐rich domain was found to follow the Williams–Landel–Ferry (WLF) laws. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1357–1364 相似文献
946.
947.
948.
Xiao Wang Xinhua Song Minfeng Jiang Pin Li Yang Hu Kai Wang Huixia Liu 《Optics & Laser Technology》2012,44(3):656-663
Laser joining parameters play a very significant role in determining the quality of laser transmission joining between PET films and 316L stainless steel plates. In the present work, Laser power, joining speed and stand-off-distance were considered as joining parameters. The parameters that influence the quality of laser transmission joining were optimized using response methodology for achieving good joint strength and minimal joint width. The central composite second-order Rotational Design (CCRD) has been utilized to plan the experiments and response surface methodology (RSM) is employed to develop mathematical relationships between joining parameters and desired responses. Based on the developed mathematical models, the interaction effects of the process parameters on laser transmission joining were investigated and optimum joining parameters were achieved. The experimental values nearly agree with the predicted values from mathematical models, indicates that the models can predict the responses adequately and optimize the key process parameters quickly. 相似文献
949.
Keyu Jiang Qin Fan Tong Chen Changxi Miao Zhenji Zhao Xielong Yang 《Hyperfine Interactions》2012,205(1-3):81-85
Two series of Fe-K catalysts for dehydrogenation of ethylbenzene to styrene were prepared with different amounts and different compounds of the additional element Ce. M?ssbauer spectroscopy has been used to determine the Fe compound in the catalyst and to investigate the effect of Ce. The catalytic properties of the catalysts have also been measured. The results show that the element Ce in the catalyst is favorable to form the predecessor of the catalytic active phase, the compound KFe11O17 and that the optimal percentage of CeO2 is 8%~15% in the catalyst which is favorable to the formation of KFe11O17 and to get better catalytic properties. 相似文献
950.
Synthesis of multi‐functionalized carbonyl compounds by palladium–catalysed γ‐substitution of MBH adducts with activated amides
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Gao Pei‐Sen Zhang Jin‐Lei Li Ning Zheng Zhan Jiang Yuan Yang Gao Zi‐Wei Zhang Weiqiang Xu Li‐Wen 《应用有机金属化学》2018,32(3)
Catalytic allylic γ‐substitution with Morita‐Baylis‐Hillman (MBH) adducts for creating a new family of unsymmetrical dicarbonyl compounds was presented in this work, in which a variety of allylated amide products were achieved in good yields and high regioselectivity with excellent linear‐to‐branched ratios. Especially, it was found that the Pd/HZNU‐Phos complex exhibited remarkably high activity (with a TON up to 16800) in this transformation between dicarbonyl amides and MBH adducts. In addition, the possibly multisite interaction between multifunctional Pd/HZNU‐Phos catalyst system and substrates might responsible for its exceptionally high efficiency in this reaction. 相似文献