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題 名 | 理論研究β-thioxoketone相關分子的enol-enethiol互變異構作用及旋轉異構作用=Enol-Enethiol Tautomerism and Rotamerization of Related β-thioxoketones: A Theoretical Study |
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作 者 | 蔡明松; | 書刊名 | 慈惠學報 |
卷 期 | 9 2013.12[民102.12] |
頁 次 | 頁82-97 |
分類號 | 348.221 |
關鍵詞 | enol-enethiol互變異構作用; 分子內氫鍵; 共振增強效應的氫鍵; Enol-enethiol tautomerism; β-thioxoketone; Rotamerism; Molecular hydrogen-bond; Resonance-assisted H-bond; |
語 文 | 中文(Chinese) |
中文摘要 | 本研究運用DFT(Density functional theory)方法探討β-thioxoketone 相關分子對enol-enethiol互變異構作用及旋轉異構作用的影響因素。在RB3LYP/6-31G**層次計算顯示在β-thioxoketone 分子的(Z)-enol的分子內氫鍵OH...S及enethiol的分子內氫鍵S-H...O比一般同類型的氫鍵強,且有低的能量障壁的質子轉移導致β-thioxoketone相關分子容易enol-enethiol互變異構作用,所以β-thioxoketone相關分子都是enol結構和enethiol結構的互變異構混合體。由於分子內氫鍵OH...S比SH...O強,因此(Z)-enol異構物比(Z)-enethiol異構物穩定,且是β-thioxoketone所有異構物中最穩定的。另外對β-thioxoketone相關分子而言,(Z)-enethiol異構物的SH...O氫鍵較弱(低於3.5 Kcal/mol),所以會形成沒有分子內氫鍵的開環結構及藉C-C單鍵旋轉產生(E)-enethiol異構物。研究也顯示enethiol異構物比enol異構物容易進行形成反式異構物。 |
英文摘要 | The enol-enethiol tautomerism and (Z) form-(E) form rotamerism of β-thioxoketones, are discussed on the basis of B3LYP/6-31G** calculations. It is shown that the enol and enethiol tautomers of the β-thioxoketones be coexist. For (Z)-enol form, the more stable tautomer among the possible isomer of β-thioxoketones. The enol and the enethiol are interconverting rapidly due to the low energy barriers within the H-bonding framework of β-thioxoketones. Computations show that the low energy barriers of proton transfer for OH...S and SH...O intrmolecularly hydrogen-bonded in β-thioxoketones, because of because of because of because of because of the more delocalized charge distribution. The analysis of results lead to that only (Z)-enethiol can by rotamerism form non-proton chelated (Z)-enethiol and (E)-enethiol. |
本系統中英文摘要資訊取自各篇刊載內容。