甲氧基的异构化:通过酸催化剂介导的分子内原子转移
Robert J Buszek1, Amitabha Sinha, Joseph S Francisco
1Department of Chemistry, Purdue University, West Lafayette, Indiana 47907-2084, United States.
酸催化剂显著降低了CH(3) O的激素异构化到CH(2) OH.的激活能量. 硫酸催化提高了超过12个数量级的反应速率,使得禁止的气相激素反应.
科学领域:
- 化学动力学 化学动力学
- 理论化学 理论化学
- 反应机制 反应机制
背景情况:
- 甲氧基 (CH(3) O) 到甲基 (CH(2) OH) 的异构化是大气化学中的一个关键反应.
- 了解激进反应机制对于预测大气组成和反应性至关重要.
研究的目的:
- 研究水,酸和硫酸对CH(3) O到CH(2) OH异构的催化作用.
- 在各种催化条件下确定这种异构化的激活能量和速率常数.
主要方法:
- 计算化学方法被用来研究反应途径.
- 单独反应和在催化剂的存在下计算了激活能量.
- 利率常数被确定为298K.
主要成果:
- 计算的激活能量从30.2 kcalmol-1 (隔离) 降至25.7 (水),4.2 (酸) 和2.3 kcalmol-1 (硫酸).
- 一个双键过渡状态被确定为降低激活能量的关键.
- 硫酸催化增加了速度常数超过12个数量级在298K.
结论:
- 酸催化,特别是硫酸的催化,极大地促进了CH(3) O基的气相异构.
- 稳定过渡状态的形成是观察到的催化效应的原因.
- 这项研究表明了酸催化激素异构化反应的可行性.
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