大学化学

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计算化学在乙醇脱水反应机理教学中的应用

李亦菲1, 冯甜甜1, 钟璐佳1, 黄秀莉1, 王启合1, 周盼盼2, 周大刚1   

  1. 1 西华师范大学化学化工学院, 四川 南充 637009;
    2 兰州大学化学化工学院, 甘肃 兰州 730000
  • 收稿日期:2025-11-25 录用日期:2026-03-06
  • 通讯作者: 周大刚 E-mail:313925019@qq.com Zhou Dagang
  • 基金资助:
    西华师范大学横向合作项目(KH2025-114)

Application of Computational Chemistry in Teaching the Mechanism of Ethanol Dehydration

Li Yifei1, Feng Tiantian1, Zhong Lujia1, Huang Xiuli1, Wang Qihe1, Zhou Panpan2, Zhou Dagang1   

  1. 1 College of Chemical Engineering, China West Normal University, Nanchong 637009, China;
    2 College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, China
  • Received:2025-11-25 Accepted:2026-03-06
  • Contact: Zhou Dagang E-mail:313925019@qq.com

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摘要： 乙醇脱水反应是高中有机化学“烃的衍生物”的重要内容，也是中学化学教学中探讨反应机理与条件控制的经典案例。但其机理常被简化为“高温成烯，低温成醚”的口诀，不能从深层次说明浓硫酸的作用以及温度对产物选择性的影响。通过密度泛函理论(DFT)计算发现：酸催化能够显著降低分子间脱水(生成乙醚)和分子内脱水(生成乙烯)的能垒；且170 °C时乙醚会逆转成碳正离子进而转化为乙烯，解释了高温下乙烯为主要产物的实验现象。

关键词: 乙醇, 计算化学, 反应机理, 乙烯, 乙醚

Abstract: The dehydration reaction of ethanol constitutes a fundamental component of the "Derivatives of Hydrocarbons" module in high school organic chemistry curricula. This reaction serves as a paradigmatic case study for examining mechanistic pathways and condition-dependent product control in secondary chemistry education. Current pedagogical approaches frequently oversimplify the mechanistic interpretation through the adage "high temperature yields alkene, low temperature yields ether," which fails to elucidate the catalytic role of concentrated sulfuric acid or the temperature-dependent product selectivity. Density functional theory (DFT) calculations reveal two critical insights: first, acid catalysis substantially reduces the activation barriers for both intermolecular dehydration (yielding diethyl ether) and intramolecular dehydration (producing ethylene); second, at 170°C, diethyl ether undergoes reversion to a carbocation intermediate, subsequently converting to ethylene. These computational findings provide a molecular-level explanation for the experimental observation of ethylene predominance under elevated temperatures.

Key words: Ethanol, Computational chemistry, Reaction mechanism, Ethylene, Diethyl ether