在H2下,从 (H2O) 2Co(dmgBF2) 2中形成一个Co-H键的证据:适用于激进循环化
Gang Li1, Arthur Han, Mary E Pulling
1Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Journal of the American Chemical Society
|August 18, 2012
概括
科巴洛克西姆利用气催化二烯的激进循环. 的吸收是速度限制的步骤,第三阶段的速度常数为106{}3) M{}-2) ·s{}-1).
科学领域:
- 有机金属化学 有机金属化学
- 激进的反应 激进的反应
- 催化剂是一种催化剂.
背景情况:
- 科巴洛克西姆是众所周知的各种有机转变的催化剂.
- 极端循环化是形成循环化合物的强大工具.
- 气 (H2) 可以参与激进反应.
研究的目的:
- 为了研究在H2.2下的二烯基基循环中cobaloximes的催化活性.
- 阐明这种催化过程的机制和动力学.
- 为了确定决定速度的步骤并量化其速率常数.
主要方法:
- 采用cobaloximes作为催化剂,在H2.2的存在下激发dienes的循环发生.
- 使用三基 (Ar3C•) 或TEMPO从中间体中抽取基 (H•).
- 进行动力学研究以确定反应顺序和速率常数.
主要成果:
- 科巴洛克西姆有效地催化了H2下的二烯的激进循环.
- 通过使用三基或TEMPO可以实现基抽象.
- 确定确定速率的步骤是吸收H2.
- 反应表现出对的二次依赖和对的第一级依赖.
- 对于H2吸收,确定了106{\displaystyle 106} (3) M{\displaystyle M}-2) ·s{\displaystyle M}-1的第三阶速常数.
结论:
- 可行的是用催化二烯与H2的激进循环.
- 该机制涉及从化中间体中抽取基.
- 的吸收是速度限制的步骤,提供了关于催化剂效率的见解.
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