理論計算模擬有機立體化學反應路徑與選擇性
| dc.contributor | 蔡明剛 | zh_TW |
| dc.contributor | Tsai, Ming-Kang | en_US |
| dc.contributor.author | 張翔凱 | zh_TW |
| dc.contributor.author | Chang, Hsiang-Kai | en_US |
| dc.date.accessioned | 2020-12-14T08:58:32Z | |
| dc.date.available | 2020-02-11 | |
| dc.date.available | 2020-12-14T08:58:32Z | |
| dc.date.issued | 2020 | |
| dc.description.abstract | 理論計算用於預測、尋找立體化學的位向選擇已行之有年，透過計算我們對微觀現象有了更進一步的了解。本篇研究以Gaussian 09為計算軟體，分為兩部分探討立體化學的反應位向，第一部份探討質子化反應(protonation)的立體位向選擇，並以不同的酸性分子：4-nitrophenol、acetic acid以及hydronium ion進行質子化反應，分子結構先以B97XD/6-31G初步優化，再以wB97XD/6-311G(d,p)做二次優化，透過分析電荷分布與過去的文獻中1，找到N-oxide與C3是可能被質子化的反應位向，以勢能面掃描與分子結構探討，說明C3的Si-face為本實驗質子化選擇性的依據，並與前人提出Re-face的選擇性進行結構比較2。最後確認反應步驟中的質子化反應與開環反應並非同步，是先進行質子化後再進行開環反應，且速率決定步驟應為開環反應，完成反應路徑分析。 第二部分探討不同配位基的Rh催化劑所產生立體產物的選擇，以及反應路徑的探討，若配位基為COD(1,5-Cyclooctadiene)，則立體產物為外消旋；若配位基為4,7,7-trimethyl-2,5-biphenylbicyclo[2.2.1]hepta-2,5-diene，則立體產物為R form，後者為我們主要的分析對象。從結構與產物的關係來判斷中間物與催化劑的可能催化位向，以B3LYP/6-31G*/SDD進行結構優化，發現可能的催化位向為between與conjugate位，再以這兩個位向進行勢能面掃描，找到between位是較為合理的催化路徑，且從掃描的能障與過渡態分子結構，支持實驗所觀察到的R form選擇性。最後再將配位基換成COD進行between位的催化反應，所得的能障也支持實驗所觀察到的外消旋。 | zh_TW |
| dc.description.abstract | Theoretical calculations have been used to predict and determine the possible orientation of organic and inorganic stereochemistry for a long time. It is especially suitable for investigating the transition state structures and reaction mechanism. This thesis study is an example of using Gaussian 09, a conventional computational chemistry package, to study the stereochemistry of an organic and inorganic reaction. In the first part, we discuss the orientation of protonation by using different acids, like 4-nitrophenol, acetic acid, and hydronium ion. All structures in this part are initially optimized at the B97XD/6-31G level, and then re-optimization by using wB97XD/6-311G(d,p). Through analyzing the charge and previous literature1, we find out N-oxide and C3 is the most probable direction for protonation. The potential energy surface scanning and molecular structure are discussed, which shows that Si-face of C3 is the direction for protonation selectivity in the experiment, and compares with the early proposed Re-face structure2. Finally, we have shown that the protonation step and the ring-opening step are asynchronous, and the ring-opening step is carried out after protonation. By using frequency analysis, the rate determining step should be a ring-opening reaction. In the second part, we discuss the selection of stereoisomers generated by Rh catalyst with different ligands. If the ligand is COD(1,5-Cyclooctadiene), the stereo product is racemic. If the ligand is 4,7,7-trimethyl-2,5-biphenylbicyclo[2.2.1]hepta-2,5- diene, the stereo product is R form, which is the main object we discuss. From the structure of intermediate and Rh catalyst, we determine some possible catalytic intermediates. All structures in this part were optimized at B3LYP/6-31G*/ SDD level. And we find out the possible catalytic directions may “between” and “conjugate”. Scanning the potential energy surface with these two directions, we find “between” is a reasonable catalytic path. And from the energy barrier and transition state structure, we support the experimental observation of R form selectivity. Finally, the ligand was replaced by COD to catalyze at the “between” position, the barrier also supports racemic observed in the experiment. | en_US |
| dc.description.sponsorship | 化學系 | zh_TW |
| dc.identifier | G060442034S | |
| dc.identifier.uri | http://etds.lib.ntnu.edu.tw/cgi-bin/gs32/gsweb.cgi?o=dstdcdr&s=id=%22G060442034S%22.& | |
| dc.identifier.uri | http://rportal.lib.ntnu.edu.tw:80/handle/20.500.12235/111085 | |
| dc.language | 中文 | |
| dc.subject | Gaussian 09 | zh_TW |
| dc.subject | 立體化學 | zh_TW |
| dc.subject | 質子化反應 | zh_TW |
| dc.subject | 勢能面掃描 | zh_TW |
| dc.subject | Gaussian 09 | en_US |
| dc.subject | stereochemistry | en_US |
| dc.subject | protonation | en_US |
| dc.subject | potential energy surface scan | en_US |
| dc.title | 理論計算模擬有機立體化學反應路徑與選擇性 | zh_TW |
| dc.title | Theoretical Calculations of Organic Stereochemistry Reaction Pathway and Selectivity | en_US |
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