溶液中SN2和Menschutkin反應的理論研究 = Theoreti...
國立高雄大學應用化學系碩士班

 

  • 溶液中SN2和Menschutkin反應的理論研究 = Theoretical Study of SN2 and Menschutkin Reactions in Solution
  • 紀錄類型: 書目-語言資料,印刷品 : 單行本
    並列題名: Theoretical Study of SN2 and Menschutkin Reactions in Solution
    作者: 顏秀娟,
    其他團體作者: 國立高雄大學
    出版地: [高雄市]
    出版者: 撰者;
    出版年: 2009[民98]
    面頁冊數: 101面圖、表 : 30公分;
    標題: Menschutkin 反應
    標題: Menschutkin reaction
    電子資源: http://handle.ncl.edu.tw/11296/ndltd/60885159496658246324
    附註: 參考書目:面77-84
    附註: 指導教授:莊曜遠
    摘要註: 本研究主要利用混成密度泛函理論 (Hybrid density functional theory, HDFT)來探討氣相和溶液中第一型SN2反應Y- + CH3X → YCH3 +X- (Y/X: F/Cl, Cl/Cl) 和 第二型 SN2(Menschutkin)反應 NH3 + CH3Cl → CH3NH3+ + Cl-。將所有參與反應的反應物、中間體、過渡態和產物,依序進行結構最佳化和振動頻率的計算。本研究第一部分探討雙分子系統的SN2反應,其類型有(R1) 對稱型SN2反應、 (R2)非對稱型SN2反應和(R3)特殊型Menshutkin反應。在continuum solvation model的理論研究當中,採用不同溶液模型估算溶質和溶劑分子或溶劑分子間的作用力,可以發現溶液中反應受溶劑效應的變化情形,並藉由反應過渡態理論(Transition state theory,TST)計算溶液中SN2反應之反應速率常數。對於對稱型SN2反應而言,計算結果可知氣相和液相的反應速率常數比為1019。對於非對稱型SN2反應中,溶液中該反應的反應速率較慢,氣相和液相反應速率常數比為1022,溶液中其親核子的強度與鹼度恰好相反,由此可以判定溶液中氯離子的反應性大於氟離子。Menshutkin反應而言,溶液中反應速率比氣相中反應速率快,其反應速率常數比為1054。 本研究第二部分探討單分子系統的SN2反應,其類型有(R4)非對稱型SN2反應和(R5)特殊型Menshutkin反應於不同solvation models的理論研究。為了避免產生置放水分子的問題,我們假設溶液中雙分子系統的SN2反應為單分子系統。根據計算結果可知R4和R5反應,使用cluster- continuum solvation model兼具兩者溶劑模型的優點來處理溶劑效應。計算結果可知R4反應的反應能障為20.59 kcal/mol,而R5反應的反應能障為14.30 kcal/mol。我們證明Cluster-Continuum Solvation Model於反應熱力學的可行性。 We apply hybrid density functional theory (HDFT) to study SN2 reactions Y- + CH3X → YCH3 +X- (Y/X: F/Cl, Cl/Cl) and Menschutkin reaction NH3 + CH3Cl→ CH3NH3+ + Cl- in gas and solution phases. In gas phase, we investigate the structures of reactants, ion-complex, transition state, and products along the reaction paths. In solution phase, we use continuum solvation models to explore the interactions between the solute and solvent molecules or the interactions between the solvent molecules. The first part of the thesis explores (R1) symmetric SN2 bimolecular reaction, (R2) asymmetric SN2 reaction and (R3) Menshutkin reaction for continuum solvation models study. By calculating the rate constant with transition state theory (TST), we find the reactant rate constant for R1 reaction, the solvation decreases reaction rate by more than 19 orders of magnitude. For R2 reaction, the solvation decreases reaction rate by more than 22 orders of magnitude. For R3 reaction, the solvation decreases reaction rate by more than 54 orders of magnitude. Menshutkin reaction in solution, the reaction rate is faster than gas phase, others is opposite. The second part of the thesis studies the (R4) SN2 and (R5) Menshutkin reaction of unimolecular in solution with different solvation models. We use MPW1K in gas phase, and three solvation models. We use microsolvation, continuum solvation models, and cluster-continuum solvation models. The calculations reproduce the best results for cluster continuum solvation model. The result show the barrier height of R4 reaction is 20.59 kcal/mol, and the barrier height of R5 is 14.30 kcal/mol. We find that the result of cluster-continuum solvation model is consistent with best reference.
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310001861296 博碩士論文區(二樓) 不外借資料 學位論文 TH 008M/0019 421202 0124 2009 一般使用(Normal) 在架 0
310001861288 博碩士論文區(二樓) 不外借資料 學位論文 TH 008M/0019 421202 0124 2009 c.2 一般使用(Normal) 在架 0
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