查询词典 samarium

And then the intermolecular reductive cyclization reaction of N,N-diethyl-o-nitrobenzenesulfonamide with nitriles promoted by samarium diiodide was studied. 2H-1,2,4-Benzothiadiazine 1,1-Dioxides were prepared in good yields under mild and neutral conditions.

然后研究了二碘化钐促进的邻硝基N，N-二乙基苯磺酰胺与腈发生的分子间交叉还原偶联反应，一步合成了2H-1，2，4-苯并噻二嗪-1，1-二氧化物。

Single-component samarium diiodide catalyst system was first used with polymerization of acrylonitrile. Adding of hexamethylphosphoramide could greatly improve reaction activity of the catalyst system. AN/Sm12 and l{IVIPA1 Sm12 molar ratios, reaction time and temperature were mainly investigated with yields and molecular weights of resultant PAN.

研究发现HMPA的加入可以极大地提高催化活性；考察了单体与催化剂(SmI2)的摩尔比例、第二组分与催化剂(SmI2)的摩尔比例、反应温度、反应时间等因素对相应聚合物的产率和分子量的影响，通过对聚合物的红外和核磁的分析，提出了&单电子转移-双阴离子引发&机理。

Treatment of dials with N-tert-butanesulfinamide, all biaryl dials were successfully converted into the corresponding bis-imines which were then treated with samarium diiodide to afford diamine products. The absolute configurations of all the intramolecular coupling products were determined by X-ray crystallography.

轴手性二醛与N-叔丁基亚磺酰胺缩合得到相应的亚胺，其为一对非对映异构体。N-叔丁基亚磺酰亚胺在二碘化钐条件下得到的偶联产物，经X-衍射也确定了其立体构型。

In chapter four, the preperation of ytterbium diiodide was examined. The reductive cleavage of Se-Se bond and S-S bond induced by ytterbium diiodide was investigated. The reaction of diselenides and disulfides with allylic bromide promoted by ytterbium diiodide was also examined. The intermolecular Barbier-type reaction induced by ytterbium diiodide was studied. In the last section of this chapter, the intermolecular reductive coupling of nitriles with azides induced by samarium diiodide was investigated.

第四章，研究了二碘化镱的制备方法，以及二碘化镱作为一种优良的单电子转移试剂在有机合成中的应用：二硒醚的Se--Se键和二硫醚S-S键的还原断裂，及其在合成烯丙基硒醚，硒代酯和烯丙基硫醚，硫代酯中的应用，实验结果表明二碘化镱也能促进分子间的Barbier反应，而文献认为二碘化镱不能促进分子间的Barbier反应；最后研究了二碘化钐促进的叠氮化合物与腈的交叉还原偶联反应，一步高收率地制备脒的方法。

Studing on samarium diiodide promoted asymmetric intramolecular reducing coupling reactions, we have made the resolution of the racemic biaryl dials by using enantiomeric N-tert-butanesulfinamine as the resolving reagent successfully and thus obtained a series of axially chiral biaryl dials with high enantiomeric excess.

中文摘要在二碘化钐促进的分子内不对称还原偶联反应中，我们不仅对联芳基二醛底物的合成路线进行了优化，还发现N-叔丁基亚磺酰胺辅基可以作为手性试剂，成功地对联芳基骨架二醛化合物进行拆分，得到高对映体过量的轴手性二醛类化合物。

To our surprise, when the amount of iodide was added to 1:1 ratio with samarium, another different reaction occurred to give the iodination product (2Z)-2-alk-2-enoates in high yields.

同样地，结构类似的三氯乙醇酰胺的酯在二碘化钐的促进下也发生了类似的还原消除反应，以高产率得到N-(2，2-二氯乙烯)酰胺，该方法特色是条件温和，反应迅速。

Methods for synthesizing of pinacol are reviewed,the difference of catalytic effects and stereoselectivity with various catalytic systems are introduced in this paper.Highlights are laid on the mechanism and stereoselectivity of new synthetic methods catalyzed by low valent Samarium, Titanium and Trimethyl chlorosilane, etc.

频哪醇合成新进展* The Recent Progress in the Synthesis of Pinacol 李有桂蒋昌盛尤田耙**(中国科学技术大学化学系合肥 230026)本文综述了合成频哪醇的方法，介绍了不同催化体系的催化效果和立体选择性的差异，着重介绍了低价钐、低价钛、三甲基氯硅烷等新的合成频哪醇反应的机理和立体选择性。

For the first time we synthesized nanoscale metal hydrides of lanthanum, neodymium, samarium, dysprosium, and ytterbium with high efficiency under mild condition by complexometric catalysis instead of traditional preparation at high temperature and high pressure. It is for the first time that we synthesized lanthanide organic compounds with catalysts or initiating agents at atmosphere and ambient temperature,and some of them are new compounds. Nanometric lanthanide metal powders are prepared by thermal decomposition of the compounds in vacuum. Differently from the traditional method, size of the products prepared by our method is less than 40nm, and the activity of the reaction is very high. They are pyrophoric at atmosphere. They can make some reactions without activity or low activity show extremely high activity .We investigated influent regulations of methods, conditions to scale and special surface.

我们首次成功地用络合催化等方法取代需在高温高压下进行的传统方法，在温和条件下高效率地合成出纳米尺寸镧、钕、钐、镝、镱的金属氢化物；首次在常压常温的条件下，通过催化、引发等方法合成镧系金属有机化合物，再将其真空热分解成功地制备了纳米尺寸的镧、钕、钐、镝、镱等金属粉末；与传统方法不同，这些方法得到的产品基本颗粒尺寸小于 40 nm，遇到空气燃烧，具有极高的化学反应活性，使原来活性很低甚至观察不到活性的反应大幅度提高反应速率和产率；考察了制备方法、制备条件等因素对晶粒尺寸、比表面积大小等的影响规律。

The application of samarium reagents in organic synthesis is one of the highlights of the methodology in organic synthesis.

钐试剂在有机合成中的应用是近年来有机合成方法学研究中的热点之一。

The application of samarium reagents in organic synthesis has been attracted more attention.

钐试剂在有机合成中的应用是当前有机化学的研究热点之一。

Heres how we put it this morning in his weekly radio and internet address.

下面就是他在今早的每周电台和网络讲话中所说的。

Messe Düsseldorf China Ltd has four representative offices in China located in Shanghai, Beijing, Guangzhou and Chongqing.

现已分别在上海、北京、广州、重庆和沈阳设立了五个代表处。