Absolute Asymmetric Synthesis Using A Cocrystal Approach

1 Results Absolute asymmetric synthesis by means of solid-state reaction of chiral crystals self-assembled from achiral molecules is an attractive and promising methodology for asymmetric synthesis because it is not necessary to employ any external chiral source like a chiral catalyst.In order to design reliably absolute asymmetric syntheses in the solid state,it is inevitable to prepare and predict the formation of chiral crystals from achiral compounds.We have prepared a number of chiral cocrystals composed of different achiral molecules,revealing that cocrystal approach is efficient to find new chiral crystals.Herein we would like to review our absolute asymmetric syntheses achieved by photodecarboxylative condensation of aralkylcarboxylic acids with aza aromatic compounds and photocyclization of alkylbenzophenones in the cocrystals.     

含硫脲基Schiff碱的合成与表征(英)(简报)

Symmetric and asymmetric derivatives of thiocarbohydrazide have broadly been studied due to their potential utility as analytical reagents. Symmetric Schiff base can be easily obtained by direct reaction.while there have many troubles in obtaining asymmetric Schiff base. The obvious difficulty in the synthesis of asymmetric Schiff base is that the straight condensation methodology used for symmetric Schiffbase is no longer applicable when some symmetric dia mines were adopted as the parent reactants in the condensation reaction. As ketone has lower chemical activities than that of the aldehyde,     

Research on Influence Factors of Surfactivity of Polyester Polyether Block Copolymer

Polyester polyether block copolymer （PPBC） was synthesized by ester-exchange and polycondensation reactions using dimethyl terephthalate （DMT）, ethylene glycol （EG） and polyethylene glycol （PEG） as monomer. The effects of PEG molecular weight, mol ratio of DMT to PEG （nDMT/nPEG）, temperature and time of polycondensation reaction and vacuum degree in the reaction system on the surface tension and critical micelle concentration （CMC） of PPBC aqueous solution were studied. It was found that both the molecular weight and the concentration of PEG can affect PPBC＇s surface activity obviously, and the optimum synthesis condition of PPBC used as surfactant is as follows： PEG molecular weight is 1 500, tool ratio of DMT to PEG is 3, temperature and time of polycondensation reaction is 260℃ × 1 h, vacuum degree of condensation reaction is 0.03-0.05 MPa. It was proved by surface tension measurement of PPBC aqueous solution that the PPBC synthesized in this condition is a good surfactant with excellent surfactivity.     

Microwave Plasma Synthesis of Nanopowders

1 Results and Discussion Nanopowders were synthesized by using microwave plasma synthesis technique.The microwave plasma was operated in atmospheric pressure at a frequency of 2.45 GHz.The reaction temperature is directly related to the power of the microwave generator that can be controlled by adjusting the actual operating current.Firstly,ionization and dissociation of precursor species will be occurred in the plasma,nucleus can then be formed by the collision of these molecules,followed by the growth of the nuclei by further collisions.Cooling gas was used to quench the as-synthesized particles in order to inhibit further particle growth,the products will then condensed in the heat exchanger and finally collected in the powder collector. The synthesis of metal nitride,metal oxide,metals[1] and metal alloy nanopowders using the microwave plasma unit was investigated,and the effect of various processing parameters such as the effect of plasma gas,carrier gas,cooling gas,precursor raw materials and feeding rate was systematically studied.Modification of the microwave plasma unit by installing a second precursor dosing device at the lower portion of the reaction chamber can be used to form core-shell structure nanopowders[2].The processing conditions can be tuned to manipulate particle size and particle size distribution of the nanopowders.Experimental evidence suggested that the effect of feeding rate,plasma gas,carrier gas and cooling gas was critical in controlling the particle size and particle size distribution during the microwave plasma synthesis.     

Facile synthesis of nanostructured LiFePO4/C cathode material for lithium-ion batteries

Nanostructured LiFePO4/C cathode material was prepared by FePO4·2H2O/C precursor by in situ restriction reaction.The synthesized LiFePO4/C cathode material presents a narrow distribution of nano-sized particles and exhibits an excellent electrochemical property with various rates.The facile synthesis route for the preparation of nano-sized LiFePO4 material has the particular advantage of simple synthesis process and low synthesis cost.     

Silicon assistant carbothermal reduction for SiC powders

The silicon assistant method to increase the reaction yield of carbothermal reduction of silica at a lower temperature is reported. The effect of silicon on the carbothermal reduction process has been investigated in detail. Compared with traditional reduction, the introduction of silicon can change the reaction path and further increase the conversion of silicon carbide at a lower temperature. It is considered that the assistant reduction consists of three steps: vaporizing and melting of silicon, formation of silicon monoxide, and synthesis of silicon carbide. The morphology of the synthesized SiC powders through the silicon assistant method can be affected apparently by the experimental temperature.     

Effect of Coordinate Bond in Molecular Recognition of Enrofloxacin with Imprinted Polymers

1 Results Molecular imprinting is a technique for the preparation of functional materials with molecular recognition properties.Molecular imprinted polymers (MIPs) have become an increasingly active field of study for the construction of new material capable of molecular recognition.In general,MIPs are synthesized by polymerization of cross-linking complexes of template molecules and functional monomers.After removing the template molecules from de polymers,binding sites are formed by functional monomer derived residues complementary for the template molecules[1]. According to the principle,the stability of monomer-template complexes present in the solution prior to polymerization as well as the polymerization reaction itself undoubtedly play a dominant role in determining the recognition performance of the polymer.     

New Approach to the Synthesis of C-Glycosides

C-glycosides are important carbohydrate mimetics and have gained considerable attention because ot their attractive biological activities as pharmaceutical targets and their resistance to enzymatic degradation in vivo. Consequently, a large number of C-glycosides have been synthesized for their bioactivity investigation, and various synthetic methodologies have been developed. As a continuation of the synthesis of novel C-glycoside derivatives using exo-glycals as the precursor, we wish to present herein new approaches to the synthesis of C-aryl aminoglycoside via the 1,3-dipolar cycloaddition （Scheme 1 ） and C-disaccharides by Suzuki cross-coupling reaction （Scheme 2）, and the synthesis of dihydropyrimidinonyl （DHPM） glycoside by the three component Biginelli reaction （Scheme 3）.     

Synthesis of SrTiO3 for immobilization of simulated HLW by SHS

Strontium titanate synroc samples were synthesized by self-propagating high-temperature synthesis (SHS). Sr directly took part in the synthesis process. As a result, the loading content issue is basically resolved. The products were characterized by density, microhardness X-ray diffraction, and scanning electron microscopy (SEM/EDS). The leaching rate was measured by the method of PCT (product consistency test). The results indicate that the Sr2+-SrTiO₃ compound is of high density, low leach rate and high stability and the synthesis process is feasible in technology and economy. It can be concluded that the strontium titanate synroc is a perfect material to immobilize HLW.     

Microstructure and wear properties of the electroslag remelting layer reinforced by TiC particles

The electroslag remelting (ESR) layer reinforced by TiC particles was obtained by electroslag remelting. The microstructure and wear properties of the ESR layer were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), and wear test. The results indicate that TiC particles are synthesized by self-propagating high-temperature synthesis (SHS) reaction during the electroslag remelting process. The size of TiC particles is in the range of 1-10 μm, and the distribution of TiC particles is uniform, from outside to inside of the ESR layer, and the volume fraction and the size of TiC particles decrease gradually. Molten iron and slag flow into porosity due to the SHS process leading to rapid densification and the elimination of porosity in the ESR layer during the ESR process. TiC particles enhance the wear resistance of the ESR layer, whereas CaF₂ can improve the high temperature lubricating property of the ESR layer.     

微波促进2-羟基-1-萘甲醛的合成

文章以2-萘酚、氯仿为原料,碱性条件下,利用微波促进Reimer-Tiemann反应合成2-羟基-l-萘甲醛,系统的研究了原料配比、反应时间、反应辐射功率对Reimer-Tiemann反应的影响。研究结果表明:利用微波加热,以无水乙醇作溶剂,碱性介质中,2-萘酚和氯仿的物质的量之比为1∶2.3,微波辐射温度设置为70℃~75℃,加热时间18m in,2-羟基-1-萘甲醛的产率可达到56.8%,与传统加热方法相比显著缩短了反应时间,产率有所增加。     

α,β-不饱和糖烯醛的合成

为探讨α,β-不饱和糖烯醛的最佳合成条件,以五、六元糖醛为起始原料,在不同温度下合成了该类化合物.结果表明,高温有助于消除反应的进行.进一步探讨了糖氧化合成不饱和糖烯醛的反应,并首次实现了由苄基保护的糖向不饱和糖烯醛的一步合成.     

几种酚类化合物甲酰化反应的研究

以2-萘酚、对苯二酚,8-羟基喹啉为原料通过改良的Reimer-Tiemann反应,合成了几种重要的药物活性有机中间体.这些有机中间体可用于多种天然产物的合成.对所得产物进行了相应的结构表征,提出了相关的反应机理.     

超声辐射水溶液中取代芳醛、芳酮缩氨基硫脲的合成

目的利用超声技术和水相体系相结合的绿色合成法优化缩氨基硫脲的合成条件,扩展超声技术在有机合成中的应用范围。方法在超声辐射下水溶液中以取代芳香醛、芳香酮和氨基硫脲为原料探索合成缩氨基硫脲的最佳条件（P=250 W,t=8～15 min）。结果合成了12种取代芳醛、芳酮缩氨基硫脲化合物,部分产物经元素分析、IR、1HNMR表征了其结构。结论该方法操作简便、反应条件温和、反应时间短、环境友好。     

带荧光基团蒽和芘的杯芳烃衍生物合成进展

杯芳烃带上荧光基团蒽和芘后,可利用荧光发射光谱及荧光强度的不同改变,对碱金属离子、胍离子、伯胺分子及羧酸衍生物加以识别,荧光型杯芳烃作为一类能发出荧光的物质常被用作荧光探针,荧光型杯芳烃的合成颇具价值．本文综述了带荧光基团蒽和芘的单酚型和间苯二酚型杯芳烃衍生物的合成进展．     

对丙型肝炎病毒具有潜在抑制作用的 L-苯丙氨酸衍生物前体的合成

丙型肝炎病毒（HCV ）感染与肝脏病变密切相关，是造成慢性肝炎、肝硬化及肝脏细胞肿瘤的主要原因之一．由于病毒自身的生物学特性，目前仍然没有有效的疫苗和治疗药物，研究开发高效的抗病毒药物具有重要意义．Reddy和他的小组设计合成了一系列 N，N-二取代的苯丙氨酸类似物，并证明了具有该种结构的化合物可对肝炎病毒聚合酶具有很好的抑制作用，以 L-苯丙氨酸为起始原料，经过酯化成氨基酸甲酯、与不同取代基的芳香醛缩合成希夫碱、将亚胺结构还原、酸化脱酯4步反应合成了8种对丙型肝炎病毒具有潜在抑制作用的此类化合物的前体，最高总产率达到77．4％．测定产物熔点，通过核磁氢谱对目标产物的结构进行表征，结果表明实现了目标化合物的合成．     

三乙醇胺催化下的反常Reimer－Tiemann反应

本文对三乙醇胺作相转移催化剂存在下的Ｒｅｉｍｅｒ—Ｔｉｅｍａｎｎ（以下简称Ｒ—Ｔ）反应进行了研究，结果表明，三乙醇胺对此反应有明显的影响，对位和邻位产物的产率是反常的。在此催化剂存在下的反常Ｒ—Ｔ反应未见报道。     

三乙醇胺催化下的反常Reimer－Tiemann反应

本文对三乙醇胺作相转移催化剂存在下的Ｒｅｉｍｅｒ—Ｔｉｅｍａｎｎ（以下简称Ｒ—Ｔ）反应进行了研究，结果表明，三乙醇胺对此反应有明显的影响，对位和邻位产物的产率是反常的。在此催化剂存在下的反常Ｒ—Ｔ反应未见报道。     

正常赖默—悌曼反应研究:超声波辐射与相转移催化合成方法

系统研究了正常及反常赖政－悌曼反应（NormalorAbnormalReliner－TiemannReavction，NRYorART）；研究了相转移住化方法和超声波辐射技术及其在正常Reliner—Tiemann（NRT）反应中的应用，从而使反应条件温和，效率增加，对邻比大，时间缩短，取得较好收效。     

水杨醛合成工艺的改进

以甲醇代替水做溶剂,对Reimer-Tiemann法合成水杨醛进行了改进,效果较好,产率达54.6%.产品进行了红外、紫外等检测,符合文献的要求.