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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
雄心勃勃的乙基N-酸碳酸盐离子:对化和热稳定性的实验和计算研究
Vladimir Benin1, Piotr Kaszynski, J George Radziszewski
1Organic Materials Research Group Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
Journal of the American Chemical Society
|November 21, 2002
概括
化N-甲四甲盐产生三种区域异构体,其比率取决于电友. 热分解路径和稳定性通过动力学和计算研究来阐明.
科学领域:
- 有机化学 有机化学
- 计算化学计算化学
- 反应机制 反应机制
背景情况:
- N-nitrosourethane tetrabutylammonium盐是一种反应性物种,在有机合成中具有潜在的应用.
- 了解化N-酸衍生物的区域选择性和分解途径对于控制反应结果至关重要.
- 之前的研究已经探讨了相关化合物的化,但对具有各种电友性的N-氨基乙烯四甲基盐缺乏全面的分析.
研究的目的:
- 为了研究N-nitrosourethane tetrabutylammonium盐与不同电友的化.
- 为了确定电友结构和溶剂对产生的区域异构体比率的影响.
- 阐明化产品和母盐的热分解机制和动力学.
主要方法:
- (1) 采用HNMR光谱学研究二甲-d2和乙-d3溶液中的化反应.
- 确定了关键中间体的热分解的第一阶动力学和激活参数.
- 在MP2 ((fc)/6-31+G ((d)//MP2 ((fc)/6-31G ((d) 层进行了气相理论计算,以分析反应机制和过渡状态.
主要成果:
- 基化产生了三种区域异构体:N-基-N-基氨基乙烯,氧和O-基酸盐,其比率取决于电友,但不取决于溶剂.
- 原始盐和O-基衍生物表现出热不稳定性,通过单分子过程分解为乙烯碳酸盐.
- 计算研究支持了一个协调的机制,具有四个中心的过渡状态,用于分解,并预测了与实验观测一致的稳定性顺序.
结论:
- N-nitrosourethane tetrabutylammonium盐化作用的区域选择性主要由电友的性质决定.
- 热分解途径涉及盐和O-基衍生物的单分子过程,具有不同的速度决定步骤.
- 理论计算为反应机制,过渡状态和研究化合物的相对稳定性提供了宝贵的见解.
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