A Convenient Synthesis of Hindered N-Aryl Substituted Cyclic Amines

An efficient and high yielding synthesis of N-substituted pyrrolidines and piperidines is described.     

Synthesis of Thia-calix[4]arene Hydroxamic Acids by Microwave Irradiation

Thia-calix[4]arene hydroxamic acids have been synthesized by partial reduction of nitro-thia-calix[4]arenes with hydrazine hydrate, Rn/Ni, and their coupling with benzoyl chloride under the influence of microwave irradiation with 90–95% yield and 3–6 min reaction time.     

微波辅助碱解荧光分光光度法快速测定河豚毒素含量

建立了一种快速、简便、灵敏地测定河豚毒素的新方法。在水和异丙醇混合碱性溶液中对河豚毒素进行微波碱解,通过测定碱解产物的量来间接测定河豚毒素的含量。结果表明:C9碱的最大激发波长为380nm,最大发射波长为496 nm,其在0.1~10μmol.L-1的浓度范围内与荧光强度呈线性关系,相关系数r=0.999 1,检测限为0.05μmol.L-1,比文献报道降低近20倍。该方法快速、灵敏和准确,可用于河豚毒素的定量检测。     

(1/2+1/2+1)腔型热阴极微波电子枪

 介绍了一种新型的轴耦合热阴极微波电子枪的设计，该枪采用了缩短首腔以及在首腔与主加速腔间插入耦合半腔的设计思想，在不破坏粒子束性能的基础上尽量减小反轰功率，给出了用Superfish 及Pamela软件进行物理设计以及粒子动力学计算的结果，在脉冲宽度为6μs, 重复频率为25Hz时，阴极上平均反轰功率为3.6W,达到设计要求。     

The Studies of Microwave Effects on the Chemical Reactions

Microwave heating involves direct absorption of energy by functional groups that bear ionic conductivity or a dipole rotational-effect, and this energy is then released into the surrounding solution. This absorption of energy causes the functional groups involved to have higher reactivity to other surrounding reactants than when they are simply incubated with the reactants at the same temperature. In other word the enhanced rate of the reaction can be due to the reactant stirred by the molecular dipole rotation and molecules themselves acting as a stirring bar. In contrast to conventional heating, the salient feature of “dipole rotation” constitutes one efficient form of “molecular agitation” or “molecular stirring” many aspects of which can be explore in chemical reactions. We will discuss some of the useful applications of this “molecular agitation” by means of microwave irradiation. Using this unique technology, we have developed: 1) a method to control the cleavage sites of peptide bonds, especially those bonds connected to aspartic acid residues inside the native peptides and proteins, 2) a method to increase coupling efficiency in solid-phase peptide synthesis using a common microwave oven, 3) a novel procedure that increases the rate of alcalase-catalyzed reactions using microwave irradiation in peptide-bond formation with proline as a nucleophile and selective benzoylation of a pyranoside derivative, 4) a procedure to solubilize and hydrolyze retrograded starch, 5) a novel procedure to enhance the rate of saponification in a serum sample for very long chain fatty acid analysis.     

MIP中一些非金属元素发射谱线特性的研究——Ⅰ.Ar MIP中S、P和I的发射谱线

本文采用超声雾化进样、水冷凝及浓H_2SO_4吸收相结合的去溶方法对S、P和I三元素在Ar MIP中的发射光谱特性进行了研究,获得了三种元素在200～600nm范围内的较详细的谱图,并求出了各谱线的相对发射强度。为了使Surfatron在最佳状态下工作,对Surfatron的调节特性也进行了考查,得到了一些有意义的结果。     

Microwave-assisted reactions： Three-component process for the synthesis of 2-amino-2-chromenes under microwave heating

2-Amino-2-chromenes are class of heterocycles that posses considerable interest as pigments,cosmetics,potential agrochemicals and being the main constituents of many natural products.Although,they are generally prepared either under conventional heating,benign reagents or very recently,a three component condensation in poly-ethylene glycol-water in the presence of nanosized magnesium oxide,most of these methods require prolonged reaction time,reagents in stoichiometric amounts and generate moderate yield...     

氯化钙在10X分子筛上的微波强化分散及其氨吸附的研究

利用干混法将氯化钙担载于10X分子筛上,通过微波法强化分散,研究了不同条件下样品的XRD图和氨吸附量,并与同样氯化钙担载量的焙烧法样品进行了比较.结果表明,微波法能显著提高CaCl2的分散度,且对应样品的氨吸附量显著提高.CaCl2在10X分子筛上的单层分散阈值在0.4 g/g～0.5 g/g之间,担载量为0.5 g/g的样品的氨吸附量最大,在35℃时达到0.575 g/g.在85 ℃时样品的吸附量都很小,这对利用低温余热脱附很有利.样品的适宜微波处理时间在10 min～20 min之间.同时,利用比表面分析和红外光谱分析证明微波法可以强化分散且不改变分子筛结构.     

Fast deprotection of phenoxy benzyl ethers in transfer hydrogenation assisted by microwave

Phenoxy benzyl ethers are easily and quickly deprotected in the presence of ammonium formate and microencapsulated Pd(0)EnCat with the assistance of microwave irradiation. This procedure can be applied in the presence of other functional groups as well. The described protocol is particularly convenient for the preparation in a parallel and automatic fashion of libraries of compounds possessing a phenol type moiety.     

微波作用下亚烃基丙二酸亚异丙酯的合成

报导了微波辐射下丙二酸亚异丙酯与羧基化合物进行了Ｋｎｏｅｖｅｎａｇｅｌ缩合反应，高产率地合成了亚烃基丙二酸亚异丙酯。