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51.
Unexpectedly Simple Synthesis of Benzazoles by tBuONa‐Catalyzed Direct Aerobic Oxidative Cyclocondensation of o‐Thio/Hydroxy/Aminoanilines with Alcohols under Air 下载免费PDF全文
Xinkang Shi Junmei Guo Dr. Jianping Liu Prof. Mingde Ye Prof. Dr. Qing Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(28):9988-9993
tBuONa‐catalyzed direct aerobic oxidative cyclocondensation reactions of readily available alcohols and o‐thio/hydroxy/aminoanilines under air have been developed and provide an efficient, practical, and green method for the synthesis of benzazoles. Mechanistic studies revealed that o‐substituted anilines promote the initial aerobic alcohol‐oxidation step, which explains the high reactivity and success of this unexpectedly simple and practical cyclocondensation method. 相似文献
52.
53.
在0.08 mol/L氢溴酸介质中,Tl Br4–和甲基绿形成稳定的蓝紫色缔合物,该缔合物被乙酸异戊脂萃取后用分光光度法测定高氯废水中的铊。在最佳吸收波长590 nm处,铊的质量浓度在0~5μg/(10 mL)范围内与吸光度呈良好的线性关系,相关系数为0.998 7,检出限为0.005 3μg/mL。测定结果的相对标准偏差为1.99%~3.38%(n=6),样品加标回收率为96.55%~98.04%。该方法操作简单,可应用于高氯废水中铊的测定。 相似文献
54.
Pickering Interfacial Catalysis for Biphasic Systems: From Emulsion Design to Green Reactions 下载免费PDF全文
Dr. Marc Pera‐Titus Dr. Loïc Leclercq Dr. Jean‐Marc Clacens Dr. Floryan De Campo Prof. Dr. Véronique Nardello‐Rataj 《Angewandte Chemie (International ed. in English)》2015,54(7):2006-2021
Pickering emulsions are surfactant‐free dispersions of two immiscible fluids that are kinetically stabilized by colloidal particles. For ecological reasons, these systems have undergone a resurgence of interest to mitigate the use of synthetic surfactants and solvents. Moreover, the use of colloidal particles as stabilizers provides emulsions with original properties compared to surfactant‐stabilized emulsions, microemulsions, and micellar systems. Despite these specific advantages, the application of Pickering emulsions to catalysis has been rarely explored. This Minireview describes very recent examples of hybrid and composite amphiphilic materials for the design of interfacial catalysts in Pickering emulsions with special emphasis on their assets and challenges for industrially relevant biphasic reactions in fine chemistry, biofuel upgrading, and depollution. 相似文献
55.
Stereoselective Synthesis of the Halaven C14–C26 Fragment from D‐Quinic Acid: Crystallization‐Induced Diastereoselective Transformation of an α‐Methyl Nitrile 下载免费PDF全文
Francis Belanger Dr. Charles E. Chase Dr. Atsushi Endo Dr. Francis G. Fang Dr. Jing Li Steven R. Mathieu Dr. Annie Z. Wilcoxen Huiming Zhang 《Angewandte Chemie (International ed. in English)》2015,54(17):5108-5111
Crystallization‐induced diastereoselective transformation (CIDT) of an α‐methyl nitrile completes an entirely non‐chromatographic synthesis of the halichondrin B C14–C26 stereochemical array. The requisite α‐methyl nitrile substrate is derived from D ‐quinic acid through a series of substrate‐controlled stereoselective reactions via a number of crystalline intermediates that benefit from a rigid polycyclic template. Therefore, all four stereogenic centers in the Halaven C14–C26 fragment were derived from the single chiral source D ‐quinic acid. 相似文献
56.
Aicha Mhamdi 《Green Chemistry Letters and Reviews》2018,11(1):12-17
A green and versatile method for the preparation of γ-hydroxyphosphonate and phosphine oxide derivatives in 5?min, is accomplished through the reduction of γ-phosphonylketones with sodium borohydride supported on alumina, at room temperature, under solvent free conditions. 相似文献
57.
Zuriati Zakaria 《中国化学会会志》2020,67(12):2241-2245
This article reflects on the Federation of Asian Chemical Societies (FACS) Citation Award Lecture delivered in the Industrial Technology Research Institute Symposium on CO2 Utilization and Green Technology during the 18th Asian Chemical Congress held in Taipei, December 12, 2019. Malaysia produces sizable amounts of palm oil and palm kernel oil, with palm fronds and tree trunks as the main waste. At the Malaysia Japan International Institute of Technology, the biomass was decomposed to produce fine chemicals, used as substrate for mushroom growth, and converted to bio-coke for heat energy. A notable difference has been found regarding the emission of greenhouse gases from a natural peat forest and those from the oil palm plantation converted from peatlands, where in the palm plantation, water table is lowered and aerobic processes occurs, resulting in more CO2 being released compared to CH4. The introduction of fertilizers to the plantation resulted in more N2O being released. The team has also pioneered a project to plant temperate vegetables. Cooling pipes (16–18°C with circulating water cooled by chiller) were embedded within each thermal conditioning soil plot. Lettuce and radish, the experimental plants, showed good growth in the thermal conditioning soil due to nitrogen-fixing bacteria, which were destroyed at a higher temperature. 相似文献
58.
《Physics letters. A》2020,384(26):126672
Ab initio density-functional theory calculations with spin polarization are performed to explore magnetic properties in zigzag green phosphorene nanoribbons (ZGPNRs) with no passivation or edge-saturated by H, OH and O chemical species. It is found that antiferromagnetic order at intra-edges is the most energetically favorable for the pristine and oxygen passivated ribbons, while H- or OH-saturated ZGPNRs show nonmagnetic order. It indicates that edge states arising from the unsaturated bonds are vital for the formation of the magnetic moment in the ZGPNRs. The magnitude of the edge magnetism in the pristine and O-saturated ZGPNRs is comparable to that in zigzag black phosphorene nanoribbons. Electronic band structures, spin densities and spd-orbital projected density of states for the studied pristine and O-passivated ZGPNRs are further analyzed to study their electronic properties. The magnetic and electronic properties discovered in the ZGPNRs may suggest potential applications in future spintronics and electronics. 相似文献
59.
利用MOCVD技术在图形化Si(111)衬底上生长了InGaN/GaN绿光LED外延材料。在GaN量子垒的生长过程中,保持NH3流量不变,通过调节三乙基镓(TEGa)源的流量来改变垒生长速率,研究了量子垒生长速率对LED性能的影响。使用二次离子质谱仪(SIMS)和荧光显微镜(FLM)分别对量子阱的阱垒界面及晶体质量进行了表征,使用电致发光测试系统对LED光电性能进行了表征。实验结果表明,垒慢速生长,在整个测试电流密度范围内,外量子效率(EQE)明显提升。我们认为,小电流密度下,EQE的提升归结为量子阱晶体质量的改善;而大电流密度下,EQE的提升则归结为阱垒界面陡峭程度的提升。 相似文献
60.
《Wave Motion》2020
Three problems for a discrete analog of the Helmholtz equation are studied analytically using the plane wave decomposition and the Sommerfeld integral approach. They are: (1) the problem with a point source on an entire plane; (2) the problem of diffraction by a Dirichlet half-line; (3) the problem of diffraction by a Dirichlet right angle. It is shown that the total field can be represented as an integral of an algebraic function over a contour drawn on some manifold. The latter is a torus. As a result, explicit solutions are obtained in terms of recursive relations (for the Green’s function), algebraic functions (for the half-line problem), or elliptic functions (for the right angle problem). 相似文献