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951.
Solid‐Phase Organic Synthesis of 1,4‐N‐Vinyl‐ and 1,4‐N‐Allyl‐Triazoles with the Sulfonate Linker
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Aiying He Shouri Sheng Zhenzhong Huang Li Liu Mingzhong Cai 《Journal of heterocyclic chemistry》2014,51(6):1862-1865
Polymer‐supported 2‐azidoethyl sulfonate and 3‐azidopropyl sulfonate reagents have been developed and applied to the solid‐phase organic synthesis of 1‐vinyl‐ and 1‐allyl‐1,2,3‐triazoles, respectively, by CuI‐mediated azide‐alkyne cycloadditions and subsequent cleavage from the polymer support through elimination reaction promoted by DBU. The advantages of this new synthetic method include simple operation and high yield of the products, as well as good stability of the reagents. 相似文献
952.
Shouri Sheng Wusheng Sheng Qiaosheng Hu Hongen Qu Mingzhong Cai 《Journal of heterocyclic chemistry》2014,51(2):315-321
A regioselective 1,3‐dipolar cycloadditions of ionic liquid‐supported vinyl ethers, derived from ionic liquid‐supported α‐phenylselenomethyl ether, with ethyl cyanoformate N‐oxide gave supported isoxazoline derivatives, which were then cleaved from the ionic liquid support under mild acidic conditions to afford ethyl isoxazole‐3‐carboxylates. This new synthetic method is simple and efficient and the products are obtained in good yields. 相似文献
953.
Synthesis of 2,5‐Diketopiperazine Derivatives Using 2‐Isocyanophenyl 4‐Methylbenzoate as a Fragrant Convertible Isocyanide
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A new protocol in which 2‐isocyanophenyl 4‐methylbenzoate is used as a convertible isocyanide for Ugi/deprotection + activation/cyclization synthesis of 2,5‐diketopiperazine derivatives has been developed. This operational simple procedure displays good functional group tolerance and avoids treatment of typically known offensive isocyanides. 相似文献
954.
Mn3O4资源丰富、结构稳定,具有较高的理论电容,是一种较有潜力的超级电容器材料,但其较差的导电性却阻碍了其在这方面应用。本论文以实心ε-MnO2微米粉体和具有亲水性的GO粉体为原料,在去离子水中通过磁力搅拌和冷冻干燥制备出具有良好接触的MnO2/GO复合粉体。然后经一步氢气还原处理,使实心ε-MnO2和GO同步转化为具有纳米多孔结构的多孔Mn3O4和RGO,从而获得分散均匀、具有高比表面积和优良导电性的高性能Mn3O4/RGO复合粉体。经电化学测试可知,Mn3O4/RGO复合粉体在2 mV/s的扫描速率下的比电容为25.2 F/g且具有较好的电容留存率。 相似文献
955.
Zhenhu Cao Yan ZhangPingan Song Yuanzheng Cai Qi GuoZhengping Fang Mao Peng 《Journal of Analytical and Applied Pyrolysis》2011,92(2):339-346
A novel metal chelate complex containing phosphorus, nitrogen and zinc (II) ion was synthesized and used as the flame retardant of low density polyethylene (LDPE). The zinc chelate complex was synthesized by reacting zinc acetate with the ligand of tetraethyl (1,2-phenylenebis(azanediyl)) bis (2-hydroxylphenylmethylene) diphosphonate (TEPAPM). The chemical structure of the target Zn-TEPAPM was confirmed by FTIR, 1H NMR, 13C NMR and 31P NMR spectra. The flame retardancy and thermal behavior of LDPE containing various amount of Zn-TEPAPM were investigated by limiting oxygen index test, thermogravimetric (TG) analysis and cone calorimetry. The results show that Zn-TEPAPM can greatly increase the thermal stability, the char formation and smoke suppression ability of LDPE. The TG curves show that even when the filler content of Zn-TEPAPM is as low as 1 wt% in LDPE, the onset degradation temperature of LDPE is increased from 429 °C to 442 °C, and the maximum degradation temperature is increased from 469 °C to 488 °C. Also, a reduction of 32% for the peak heat release rate (PHRR) is obtained in the cone test. Moreover, Zn-TEPAPM is demonstrated to be a very effective synergist of ammonium polyphosphate (APP). When 1 wt% of Zn-TEPAPM was introduced into the LDPE/APP (mass ratio 80/19) blend, the PHRR value is reduced by 32%, compared with that of LDPE/APP blend without Zn-TEPAPM, and the char layer becomes more compact and intact. 相似文献
956.
A simple, rapid and sensitive CE-ESI-MS method for the simultaneous analysis of seven stimulants and narcotics (amphetamine, ephedrine, methadone, pethidine, tetracaine, codeine and heroin) was developed. The CE-ESI-MS experimental conditions were optimized as follows: 20?mmol/L ammonium acetate with pH 9.0 as running buffer, the separation voltage of 22?kV and the sheath liquid of isopropanol/water (1:1 v/v) containing 7.5?mmol/L acetic acid with 3.0?μL/min flow rate. Under the optimized conditions, the stimulants and narcotics were well separated within 4.6?min using a 70-cm length fused-silica capillary (50?μm id). The detection limits (S/N=3) of the CE-ESI-MS analysis were in the range of 0.40-1.0?ng/mL. Method repeatability of intra-day and inter-day was satisfactory. The recoveries obtained from the analysis of spiked urine samples were between 84.1 and 108%. The developed method was successfully applied for the simultaneous analysis of methadone, pethidine and codeine and their in vitro metabolites. 相似文献
957.
Cluster studies have attracted much interest in the past decades because of their extraordinary properties. To describe the interaction between atoms or molecules and predict the energies and structures, potential functions are developed. However, different potentials generally produce different structures and energies for a cluster. To study the effect of potentials on the structure of a cluster, He clusters in the size range of 13-140 are investigated by Lennard-Jones (LJ), Pirani, and Hartree-Fock-dispersion individual damping (HFD-ID) potential with dynamic lattice searching (DLS) method. Potential function curves, cluster structures, bonds, and energies of the global minima are compared. The results show that cluster energies decrease with the values of the potential functions, the differences between structures depend upon the disagreements of the potentials, and the preferable motif of a cluster changes from icosahedron to decahedron with the increase of the derivative of the short-range part of the potentials. 相似文献
958.
Abstract
A tetrazole-supported polymeric ligand has been synthesized. The palladium complex derived from the polymeric material has been evaluated as a catalyst for the Heck reaction of aryl iodides and bromides with styrene to provide the corresponding products in high yields. The reaction proceeded smoothly in the presence of 1 mol% with respect to Pd of catalyst in DMF at 125 or 140 °C within 1–3 h. Recycling studies showed that the catalyst can be readily recovered and reused for several times without significant loss of catalytic activity. 相似文献959.
Sheng-Li Chen Haitao Wang Guimei Yuan Zhiqing Wang Zhi Cai 《Transition Metal Chemistry》2011,36(4):441-445
Macro-/mesoporous Al2O3 supports were prepared by using monodisperse polystyrene (PS) microspheres as a template. The pore volume and BET surface
area of the Al2O3 supports increased considerably with increasing amounts of the PS microspheres; further investigation showed that PS template
only increased the volume of macro-pores but did not change the volume of meso-pores or micro-pores. Macro-/mesoporous Re2O7/Al2O3 metathesis catalysts were prepared through loading Re2O7 onto the as-prepared macro-/mesoporous Al2O3 supports, and their catalytic performance was tested in a fixed-bed tubular reactor using the metathesis of normal butylenes
as a probe reaction. The results showed that the prepared macro-/mesoporous Re2O7/Al2O3 catalyst had high activity with consistent selectivity; propylene and pentene accounted for more than 90 wt% of the metathesis
products, while the amount of ethylene plus hexane was less than 10 wt%, the majority of which was hexane. These Re2O7/Al2O3 catalysts had not only higher activity, but also longer working life span and higher tolerance to carbon residues than conventional
Re2O7/Al2O3 catalysts. 相似文献
960.
A facile and high-throughput strategy is presented to fabricate three-dimensional (3D) hierarchically porous Ag films, with clean surfaces, via plasma etching Ag-coated electrospun nanofiber template. The films are built of Ag porous nanotubes and are homogeneous in macro-size but rough and porous in nanoscale. Each nanotube-block is micro/nanostructured with evenly distributed nanopores on the tube walls. The film architecture (or the shape, arrangement, and distribution density of porous nanotubes; the number and size of nanopores) can be easily controlled by the nanofiber-template configuration, Ag coating, and plasma etching conditions. Such hierarchically porous films could be very useful, such as in catalysis, sensors, and nanodevices. They have exhibited significantly structurally enhanced surface-enhanced Raman scattering performance with good stability and reproduction, and shown the possibility of molecule-level detection. Also, the strategy is universal for fabricating other hierarchically structured 3D metal porous films, such as porous Ag hollow sphere arrays. 相似文献