乳酸乙醇在气相中稳定,但在溶液中极其不稳定
Frantisek Turecek1, Shetty Vivekananda, Martin Sadílek
1Department of Chemistry, Bagley Hall, Box 351700, University of Washington, Seattle, Washington 98195-1700, USA. turecek@chem.washington.edu
Journal of the American Chemical Society
|October 31, 2002
概括
第一个稳定的乳乙醇产生和特征,揭示了独特的气相稳定性和溶液中显著的酸度. 这些发现解释了为什么在液体研究中很少检测到乳乙醇.
科学领域:
- 物理化学 物理化学
- 有机化学 有机化学
- 计算化学的计算化学
背景情况:
- 乳乙醇,乳的乙醇分离体,在历史上一直难以捉摸,难以检测.
- 了解它们的特性对于理解乳化学和反应性至关重要.
研究的目的:
- 为了产生和描述第一个代表性的乳乙醇,2-氧醇-2- (C(5) -1).
- 通过计算来研究气态和水态乳乙醇 (C(4) - 1至C(6) - 1) 的酸性质.
- 阐明导致溶液中乳乙醇难以捉摸的因素.
主要方法:
- 使用中和再电离质谱法生成气相和表征.
- 对于热力学性质的初始量子化学计算 (QCISD ((T)/6-311+G ((3df,2p))
- 在气相和水溶液中计算酸性质.
主要成果:
- 成功生成了2-Hydroxyoxol-2-ene (C(5)-1,并显示在气相中稳定.
- 乳乙醇具有较高的气相质子亲和度 (933-944 kJ mol-1) 和酸度 (1401-1458 kJ mol-1).
- 在水溶液中,乳乙醇的酸性明显高于它们的母乳 (15-20 个数量级),pK (a) 值在 5.6 到 14.5.5 之间.
结论:
- 乳酸乙醇是气相中稳定的物种.
- 它们在性溶剂中的高酸度和度解释了它们的短暂性质和难以在溶液中检测到的难度.
- 这项研究提供了对乳乙醇化学的基本见解.
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