用水性H2O2和高度选择性的表面改性TaSBA15异质催化剂氧化烯酸的动力学和机制
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|July 30, 2008
概括
这项研究详细介绍了使用Bu(cap) TaSBA15催化剂的环烯环氧化动力学. 反应遵循埃利-里达尔机制,显示了对环素和H2O2度的和动力学.
科学领域:
- 不同质的催化剂.
- 绿色化学是一种绿色化学.
- 反应动力学反应动力学
背景情况:
- 环烯环氧化是有机合成中的一个关键转化.
- 开发高度选择性和稳定的催化剂对于高效的环氧化是至关重要的.
- 水性H2O2提供了一个环保的氧化剂,但催化剂的稳定性和活性是挑战.
研究的目的:
- 用Bu(cap) TaSBA15催化剂与水性H2O2.2一起研究环烯环氧化反应的反应动力学.
- 阐明反应机制并确定关键中间体.
- 评估催化剂对H2O2分解的稳定性.
主要方法:
- 涉及不同反应剂度和催化剂负荷的动力学研究.
- 质子核磁共振 (IH NMR) 谱学用于研究H2O2分解.
- 紫外线可见吸收率和扩散反射率紫外线可见 (DRUV-vis) 谱学以表征Ta中心和中间体.
主要成果:
- 发现反应动力学在Ta (V) 表面覆盖面上是第一阶的.
- 观察到的和动力学与环素和H2O2度有关.
- 与未经修改的催化剂相比,Bu(cap) TaSBA15催化剂显示了最小的H2O2分解.
- 鉴定出一种以TaV为基础的环氧化中间体,被提出为TaVeta2-O2.
结论:
- 环氧化动力学可以通过Eley-Rideal机制或双位移机制来描述.
- 在Bu(cap) TaSBA15催化剂表现出高选择性和稳定性循环烯环氧化.
- 鉴定到的基于Ta (V) 的中间体为我们提供了对催化循环的洞察.
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