第一原理探討乙醛分子於氧化鋅團簇[(ZnO)_(12)]上的縮合反應機構

A First-principle Calculation of the Conversion Reactions of Acetaldehyde on (ZnO)_(12) Cluster

葉丞豪(Chen-Hao Yeh)

《化學》 78卷2期 (2020/06) Pp. 155-162

https://doi.org/10.6623/chem.202006_78(2).004

摘要

氧化鋅在催化Aldol或是Knoevenagel縮合反應上是個有效的催化劑並且還能應用於感測醇類或醛類分子的感測器上。本工作中我們將利用第一原理理論計算探討乙醛分子在(ZnO)_(12)團簇上進行吸附以及C-C縮合反應的可能反應路徑。首先在乙醛分子的吸附上，乙醛能夠依靠自身的孤對電子與(ZnO)_(12)團簇上的鋅原子作用。透過凡德瓦力修正計算，乙醛分子能夠在(ZnO)_(12)團簇上具有約-0.60至-0.73 eV的吸附能。此外在乙醛的轉換反應上，我們考慮乙醛與乙醛能夠自身進行Aldol縮合反應，且第一步脫氫的活化能亦不大。因此乙醛能夠克服一系列不大的活化能經Aldol反應機構自身結合形成巴豆醛以及3-hydroxybutanal兩種產物，透過我們的計算結果發現生成3-hydroxybutanal為比較可能的反應路徑。

關鍵字

第一原理計算 ； 氧化鋅團簇 ； 乙醛 ； Aldol縮合反應

並列摘要

Zinc Oxide was an efficient catalyst for the aldol or Knoevenagel condensation reaction and could also be applied as the sensor for detecting alcohol or aldehyde. In this work, we performed first-principles calculations to investigate the adsorption of acetaldehyde molecules on (ZnO)_(12) cluster and the possible reaction mechanisms of their C-C condensation reactions. First, in the adsorption of acetaldehyde molecule, acetaldehyde can adsorb on the (ZnO)_(12) cluster via its lone pair electrons to interact with zinc atoms on the (ZnO)_(12) cluster. By mean of the Van der Waals interaction correction, the acetaldehyde molecule can possess the adsorption energy of around -0.60 to -0.73 eV on the (ZnO)_(12) cluster. In addition, in the conversion reaction of acetaldehyde, we consider that acetaldehyde and acetaldehyde can perform Aldol condensation reaction by themselves, and the activation energy of the first C-H dehydrogenation is not too large. Therefore, acetaldehyde can overcome various small activation energies to form the crotonaldehyde and 3- hydroxybutanal via the Aldol condensation mechanism. Based on our calculation results, it is found that the formation of 3-hydroxybutanal is a more favorable reaction path than that of forming crotonaldehyde.

並列關鍵字

First-principle calculation ； ZnO cluster ； Acetaldehyde ； Aldol condensation