氧鎓

The mechanism of ring-opening cationic polymerization reaction of tetrahydrofuran and butylene oxide was analyzed on the basis of electronic microstructures by using frontier orbitaltheory.

求取了四氢呋喃和环氧丁烷单体与仲氧鎓离子反应的过渡态，并根据频率分析和内禀反应坐标计算对过渡态的合理性进行了确认。

Based on density functional theory calculation with periodic boundary conditions, the possibility of the direct coupling of methanol into ethene by oxonium ylide mechanism was investigated.

采用基于周期性边界条件的密度泛函理论研究了HSAPO-34分子筛上甲醇通过氧鎓叶立德机理直接耦合生成乙烯的可能性。

It is thus concluded that the methanol to olefin reaction cannot follow the oxonium ylide mechanism.

因此，甲醇制烯烃催化过程不可能遵循氧鎓叶立德机理。

Thepotential energy surface of these reactions were plotted, and the energy barrier of the reaction between THF and secondary oxonium ion was determined to be 182.0.116 kJ/mol.

本文进一步对四氢呋喃阳离子开环聚合反应过程中，氧鎓离子与水反应的机理进行了分析。

As to butylene oxide and secondary oxonium ion the barrier was determined to be 92.672kJ/mol.The reaction between oxonium ion and water in the polymerization of THF was investigated too.

结果表明，与四氢呋喃单体相比，水更容易与氧鎓离子发生反应，因此可以用水作为中止剂，来控制聚合产物的分子量。

By using density functional theory B3LYP/6-311G++method, the geometric configuration was optimized for tetrahydrofuran、butylene oxide、 secondary oxonium ion and tertiary oxonium ion. And parameters about the electronic structure, bondlength, energy of frontier orbital of these species were determined.

采用DFT中的B3LYP/6-311G++方法对四氢呋喃和环氧丁烷单体、仲氧鎓离子以及叔氧鎓离子进行了几何构型的全优化，确定了各个构型的电子结构、键长和前线轨道能量等参数，并运用前线轨道理论从微观层次上分析了四氢呋喃和环氧丁烷的阳离子均聚反应机理。

The calculated results indicate that the energy bathers for the formation of dimethyl ether and trimethyl oxonium ion inside HSAPO-34 zeolite are 1.68 and 0.93 eV, respectively. The suggested intermediate oxonium ylide is very unstable and the energy barriers for the formation of C-C bond are over 3.0 eV by concerted pathway.

结果表明，二甲醚和三甲基氧鎓离子在HSAPO-34分子筛上的生成能垒分别为1.68和0.93eV，中间体氧鎓叶立德不能稳定存在，同时表明C-C键通过协同反应形成的能垒均超过3.0ev。

A preliminary mechanism for the photo-initiated polymerization of BVE by pyrylium salt was also discussed.

文中还对氧鎓盐光引发BVE聚合的机理进行了初步讨论。

Because,the amount of double bond of BVE decreases in the process of BVE polymerization,therefore,in the same time the quenched flu-orescence of pyrylium salt can be recovered gradually.

由于在BVE的聚合过程中，被猝灭的氧鎓盐荧光会因BVE聚合、双键减少而使氧鎓盐荧光逐步恢复。

A group of pyrylium salts with different substituents has been synthesized in this work. Their fluorescence life time, quantum yield and quenching constant by BVE have also been measured. It was found that a strong interaction was observed between BVE and pyrylium salt which contains an electron-withdrawing group, and contrary, the introduction of electron-repulsive groups to the pyrylium salt will decrease this effect. It indicated that these reactions possess the characteristic of electron transfer.

本工作合成了一组带不同取代基的氧鎓盐化合物，并对它们的荧光寿命、荧光量子产率以及用丁基乙烯基醚进行猝灭的荧光猝灭常数进行了测定，发现带拉电子基的氧鎓盐化合物和BVE间存在着较强的相互作用，相反，推电子基的引入则减弱了这种影响，表明反应具有电子转移性质。

She gently rebuff ed him, but agreed that they could be friends

她婉言拒绝了，但同意作为朋友相处。

If in the penal farm, you were sure to be criticized.

要是在劳改农场，你等着挨绳子吧！