铂催化重述—催化烯烃氢化硅烷化的原理,ACS Catalysis

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铂催化重述—催化烯烃氢化硅烷化的原理
ACS Catalysis ( IF 11.3 ) Pub Date : 2016-01-26 00:00:00 , DOI: 10.1021/acscatal.5b02624
Teresa K. Meister , Korbinian Riener , Peter Gigler ₁ , Jürgen Stohrer ₁ , Wolfgang A. Herrmann , Fritz E. Kühn

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C–C多重键的氢化硅烷化是工业中均相催化的最重要应用之一。该反应的特征在于其原子效率，广泛的底物范围和广泛的应用。迄今为止，工业仍然依赖于半个多世纪以前开发的高活性铂基系统。尽管广泛的合成应用迅速发展，但对催化反应途径的基本了解的发展却是困难而缓慢的，特别是对于工业上高度相关的卡斯泰特催化剂而言。在这项工作中，进行了详细的机械研究，揭示了使用Karstedt催化剂作为铂源的铂催化氢化硅烷化的几个新方面。^两次H标记实验的组合，共^195个Pt NMR研究和深入的动力学研究为进一步发展公认的Chalk-Harrod机理提供了基础。结论是，烯烃的配位强度对反应动力学起决定性作用。此外，证明了如何从动力学数据中得出活性催化剂种类的独特结构特征。氘标记实验中的主要动力学同位素效应以及特征产物分布得出的结论是，铂催化的氢化硅烷化的限速步骤实际上是烯烃插入Pt-H键而不是还原消除产物在所研究的烯烃/硅烷组合中的含量。

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Platinum Catalysis Revisited—Unraveling Principles of Catalytic Olefin Hydrosilylation

Hydrosilylation of C–C multiple bonds is one of the most important applications of homogeneous catalysis in industry. The reaction is characterized by its atom-efficiency, broad substrate scope, and widespread application. To date, industry still relies on highly active platinum-based systems that were developed over half a century ago. Despite the rapid evolution of vast synthetic applications, the development of a fundamental understanding of the catalytic reaction pathway has been difficult and slow, particularly for the industrially highly relevant Karstedt’s catalyst. A detailed mechanistic study unraveling several new aspects of platinum-catalyzed hydrosilylation using Karstedt’s catalyst as platinum source is presented in this work. A combination of ²H-labeling experiments, ¹⁹⁵Pt NMR studies, and an in-depth kinetic study provides the basis for a further development of the well-established Chalk–Harrod mechanism. It is concluded that the coordination strength of the olefin exerts a decisive effect on the kinetics of the reaction. In addition, it is demonstrated how distinct structural features of the active catalyst species can be derived from kinetic data. A primary kinetic isotope effect as well as a characteristic product distribution in deuterium-labeling experiments lead to the conclusion that the rate-limiting step of platinum-catalyzed hydrosilylation is in fact the insertion of the olefin into the Pt–H bond rather than reductive elimination of the product in the olefin/silane combinations studied.

更新日期：2016-01-26

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