查询词典 lewis acid

The new Lewis acid centers are active for aromatization of propane.

新增加的L酸中心可能是芳构化反应的活性中心。

First, the preparation of l,2-dichloro-4-nitrobenzene, which l-chloro-4-nitrobenzene reacted with chlorine in a self-designed chlorinator, in presence of Lewis acid catalyst,.was investigated. By means of the Orthogonal Experiments design and single factor experiments, the influence of several reaction variables on the yield were examined and the optimum reaction conditions under the intervallic operation were obtained, the yield of l,2-diehloro-4-nitrobenzene was 83.26%.

为此，本文首先在自行设计的塔式氯化器中，以对硝基氯苯为原料，路易氏酸作催化剂，分子氯氯化合成3，4-二氯硝基苯(合成3-氯-4-氟-硝基苯的原料)，根据该氯化过程特征，利用正交试验设计方法结合单因素实验考察了有关因素对氯化过程的影响，优化得到了最佳的氯化工艺条件，3，4—二氯硝基苯的收率可达83.26％。

The results showed that hydrogen peroxide, silanols species and TiO〓 didn't have solvolysis activity of propylene oxide. While framework Al, coordinatively unsaturated Ti〓 ions as Lewis acid sites in the framework, Ti-OH and the five member ring active titanium species formed by TS-1, hydrogen peroxide and solvent can catalyze the solvolysis of propylene oxide.

研究结果表明：原料双氧水和TS-1沸石上的SiOH和TiO〓对环氧丙烷溶剂解反应无催化活性；而下列物种对环氧丙烷溶剂解反应具有催化活性：TS-1中的骨架铝，沸石骨架中配位不饱和的Ti〓形成的L酸中心，TS-1水解产生的钛羟基和由TS-1，双氧水和溶剂相互作用所生成的五元环中间活性钛物种。

The amount and strength of Lewis acid of titania/silica decreased with increase of content of silica.

含锑的化合物由于可能会对环境和人体造成危害，而引起人们的广泛关注。

Boron trifluoride diethyl etherate solution is a middle strong Lewis acid together with good ionic conductivity and good electrocatalytic properties.

摘 要：在过去的20 多年中，导电高分子因具有重要的学术意义和应用价值受到了广泛关注。

This dissertation is mainly focused on the reactivity of methylenecyclopropanes and comprises six parts. 1 The reactions of methylenecyclopropanes with phenylsulfenyl chloride, phenylselenyl chloride and diphenyl diselenide; 2 The coupling reactions of the ring-opening products derivated from methylenecyclopropanes; 3 The palladium-catalyzed ring-enlargement of mono-aryl group substituted methylenecyclopropanes to cyclobutenes. 4 The gold-catalyzed domino ring-opening and ring-closing hydroamination of methylenecyclopropanes with sulfonamides; 5 The Lewis acid-catalyzed reactions of mono-aryl group substituted methylenecyclopropanes with diethyl ketomalonate in the presence of water; 6 The iodobenzene diacetate mediated novel 1,3-dipolar cycloaddition of methylenecyclopropanes, vinylidenecyclopropanes, and methylenecyclobutane with phthalhydrazine.

本论文主要研究了亚甲基环丙烷类化合物的一些化学反应性能，共由以下六部分组成：1、亚甲基环丙烷类化合物与苯硫氯、苯硒氯及二苯基二硒的反应；2、亚甲基环丙烷类化合物开环产物的偶联反应；3、单芳基取代的亚甲基环丙烷类化合物在钯催化剂作用下的扩环反应；4、金化合物催化磺酰胺对亚甲基环丙烷类化合物的串联开环关环氨氢化反应；5、路易斯酸催化亚甲基环丙烷类化合物与丙酮二羧酸二乙酯在有水存在下的反应；6、醋酸碘苯促进的亚甲基环丙烷类化合物、亚乙烯基环丙烷类化合物及亚甲基环丁烷类化合物与邻苯二甲酰肼的新型1，3-偶极环加成反应。

The organoboron compounds in this paper are based on triarylboranes, boronic acids and boronic esters. The structure-property relationship and sensing mechanism are elucidated. Organoboron compounds as Lewis acid can be used as fluoride probe with high sensitivity and selectivity because they have a unique LUMO in which the π-conjugation is divergently extended through the vacant p-orbital of the boron atom. The complexation of the boron π-electron systems with fluoride ion would interrupt the π-conjugation extended through the boron atom, causing the change of photophysical properties.

介绍了基于三芳基硼化合物、硼酸和硼酸酯的有机硼化合物在氟离子检测中的应用，评述了这些化合物的结构和检测性能之间的关系，讨论了检测机理，即有机硼化合物中硼原子空的p轨道使其作为路易斯酸能够选择性地结合氟离子，硼原子与氟离子的结合破坏了硼中心与芳香取代基的p-π共轭，引起有机硼化合物光物理性质的变化，从而实现对氟离子的高选择性检测。

The transfer of R group from XZnR occurrs from the same face as the oxygen of epoxide and results in a syn addition since organozinc reagents XZnR could act as a Lewis acid system as well as being nucleophilic in character.

我们制备一类新型有机锌试剂，研究它们在适宜的反应条件下，直接对环氧化合物进行开环反应，得到顺式开环产物，实现了有机金属试剂的立体选择性顺式开环。

The free phosphonic groups shielded most of the Lewis-acid sites on the surface of zirconia and imparted negative charges on the surface at high pH, resulting in excellent resolution for phenols and a great improvement for the separation of benzoic acids.

在该固定相上，酸性化合物的色谱性能得到明显改善，硝基酚、苯二酚等在氧化锆上通常难以洗脱的酚类化合物，均得到了高效分离。

Solid acid-base catalysts instead of liquid Bronsted and Lewis acid/base catalysts is one of the most important ways with the direction of the development of green chemistry.

而用固体酸碱代替液体酸碱催化有机反应是实现环境友好的一条重要途径，符合绿色化学的发展方向。

With Death guitarist Schuldiner adopting vocal duties, the band made a major impact on the scene.

随着死亡的吉他手Schuldiner接受主唱的职务，乐队在现实中树立了重要的影响。

But he could still end up breakfasting on Swiss-government issue muesli because all six are accused of nicking around 45 million pounds they should have paid to FIFA.

不过他最后仍有可能沦为瑞士政府&议事餐桌&上的一道早餐，因为这所有六个人都被指控把本应支付给国际足联的大约4500万英镑骗了个精光。