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541.
α,β‐Unsaturated aldehydes reacted with diimide (diazene) in the presence of optically active ammonium salt 1 as a catalyst to give the corresponding saturated aldehydes in excellent yields and up to 98 : 2 er. Attractive features of the asymmetric transfer hydrogenation are its high yields, and chemo‐, and enantioselectivities. 相似文献
542.
A. Leineweber 《Journal of solid state chemistry》2003,176(1):198-202
A re-interpretation and re-evaluation of single-crystal X-ray diffraction data of a previously reported ‘(NH4)2(NH3)[Ni(NH3)2Cl4]’ (J. Solid State Chem. 162 (2001) 254) give a new formula (NH4)2−2z[Ni(NH3)2]z[Ni(NH3)2Cl4] with z=0.152. This new formula results from defects in an idealized ‘(NH4)2[Ni(NH3)2Cl4]’ basic structure, where two adjacent NH4+ cations are replaced by one Ni(NH3)22+ unit. Cl− anions from the basic structure complete the coordination sphere of the new Ni2+ to [Ni(NH3)2Cl4]2−. 相似文献
543.
Chetan K. Khatri Santoshkumar M. Potadar Ganesh U. Chaturbhuj 《Tetrahedron letters》2017,58(18):1778-1780
This is the first-time ammonium thiocyanate (NH4SCN) has been used as a self-promoting reactant for the synthesis of 3,4-dihydropyrimidin-2(1H)-thiones. This report describes a greener, efficient and economic protocol for one pot three-component synthesis of Biginelli compounds using various aldehydes, β-ketoesters and ammonium thiocyanate. Ammonium thiocyanate being a weak acid, accelerate the rate of reaction to obtain Biginelli compounds in solvent-free condition at 110 °C. The key advantages of the present method are high yields, short reaction time, solvent free condition, easy workup and ability to tolerate a variety of functional groups. Ammonium thiocyanate is readily available, cheaper, safer and industrial acceptable material which gives economical as well as ecological rewards to the present method. 相似文献
544.
A nine-step (longest linear) batch total synthesis of the cyclic hexadepsipeptide (−)-enniatin B is described. The synthesis minimizes precipitation during reaction conditions for adaptability to flow synthesis. The route was used to prepare >100 mg of the natural product. 相似文献
545.
以多聚甲醛、丙烯胺、苯酚为原料,通过Mannich反应合成烯丙基型苯并噁嗪单体(Bala),并通过核磁共振氢谱(~1H-NMR)确定了其化学结构.将Bala在聚磷酸铵(APP)原位开环聚合后,制备APP微胶囊(BMAPP).傅里叶变换红外(FTIR)和静态接触角测试表明,Bala在APP表面成功聚合,并有效提高APP的疏水性,与纯APP相比,BMAPP的接触角从10.8°提高到了71.3°.将BMAPP添加到环氧树脂(EP)中,制备EP/BMAPP复合材料.通过热重分析仪(TGA)、垂直燃烧(UL-94)、极限氧指数(LOI)、锥型量热仪(CONE)和动态热机械分析仪(DMA)对EP和EP/BMAPP的热性能以及燃烧性能进行对比分析.结果显示,10%的BMAPP的成炭效果最佳,有良好的阻燃性能,可使EP的LOI值从22.6%提高到33.6%,并通过UL-94 V-0级,600°C下残炭率达26.3%.同时,BMAPP可大幅度降低EP燃烧过程中烟密度和热释放速率,提高EP的玻璃化转变温度(T_g).BMAPP/EP-10%中,PBala和APP协同后使EP热释放速率峰值(PHRR)由1247 kW·m~(-2)降低到434 kW·m~(-2),生烟速率(SPR)降低67%左右,T_g从169°C提高到了173°C. 相似文献
546.
Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO_2 nanospheres(φ:30-50 nm,wall thickness:8-15 nm,and cavity diameter:10-20 nm).The effect of HCOONH_4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed. 相似文献
547.
548.
Hydrothermal method synthesis of α-MnO2 nanowires has been achieved at different temperatures in this work. X-ray diffraction and transmission electron microscopy confirmed the pure phase of the α-MnO2 nanowires. All of the samples crystallized in a single-phase nanowires shape. The α-MnO2 nanowires diameter increased from 11 nm to 21 nm with the increase in hydrothermal temperature from 120 °C to 200 °C. The α-MnO2 catalytic activity on the decomposition of ammonium perchlorate (AP) was characterized through thermogravimetric analysis. The decomposition rate of AP with the addition of α-MnO2 was size relative. The 11 nm MnO2 nanowires exhibited the best catalytic activity, which lowered the high-temperature peak of AP by 130 °C. 相似文献
549.
A Facile and One‐pot Synthetic Route to Functionalized Ethyl 3‐(Alkanoyl)‐2‐(alkyl imino)‐2,3‐dihydrothiazole‐4‐carboxylate Derivatives under Mild,Solventand Catalyst‐free Conditions 下载免费PDF全文
A new one‐pot, four‐component synthetic rout is reported for the preparation of functionalized N‐acyl‐2alkylimino‐2,3‐dihydrothiazole derivatives from the reaction between acid chlorides, ammonium thiocyanate, primary alkylamines, and ethyl bromopyruvate under mild, solvent‐ and catalyst‐free conditions at room temperature. This completely green and efficient straight forward procedure led to the desired products in good to high yields without any need to catalyst or solvent assistance and no by product was observed in all the reactions 相似文献
550.
A Novel One‐Pot Sulfonyloxylactonization of Alkenoic Acids Mediated by Hypervalent Iodine Species Generated in situ from Ammonium Iodide 下载免费PDF全文
A novel and efficient one‐pot procedure was designed for the sulfonyloxylactonization of alkenoic acids by the reaction of alkenoic acids with m‐chloroperbenzoic acid and sulfonic acids in the presence of a catalytic amount of ammonium iodide in a mixture acetonitrile/2,2,2‐trifluoroethanol (4 : 1) at room temperature for 24 h, which provided the corresponding sulfonyloxy lactones in moderate‐to‐good yields. 相似文献