Palladium Nanoparticle-Embedded Polymer Thin Film 鈥淒ip Catalyst鈥?for Suzuki鈥揗iyaura Reaction
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- 作者：E. Hariprasad ; T. P. Radhakrishnan
- 刊名：ACS Catalysis
- 出版年：2012
- 出版时间：June 1, 2012
- 年：2012
- 卷：2
- 期：6
- 页码：1179-1186
- 全文大小：400K
- 年卷期：v.2,no.6(June 1, 2012)
- ISSN：2155-5435
文摘
Hallmarks of a successful catalyst include simplicity of design and low cost of fabrication, high efficiency, facile recovery and extensive reusability, amenability to monitoring between reuses, and ease of scale up. Even though the number of palladium nanoparticle based catalysts reported for the Suzuki鈥揗iyaura reaction has grown exponentially in recent years, the aforesaid criteria are rarely met in a single system. We present a palladium nanoparticle-embedded polymer thin film which functions as a highly efficient and reusable 鈥渄ip catalyst鈥?for the Suzuki鈥揗iyaura reaction. The multilayer free-standing nanocomposite thin film is fabricated using a simple in situ process through thermal annealing of a spin-coated film of poly(vinyl alcohol) (PVA) containing the palladium precursor. Fabrication parameters of the Pd-PVA film are optimized for enhanced catalyst efficiency. The catalyst is shown to produce very high yield, turn over number and turn over frequency in the prototypical reaction of iodobenzene with phenylboronic acid. The 鈥渄ip catalyst鈥?film is easily retrieved from the reaction system and reintroduced in successive batches; the high efficiency is retained beyond 30 cycles. The thin film structure enabled convenient catalyst monitoring by spectroscopy and microscopy between reruns. Efficient use of the catalyst up to 5 mmol scale reaction is demonstrated. A simple figure-of-merit is formulated to quantify the catalyst performance, and the present catalyst is evaluated in the context of those reported earlier. Preliminary exploration of the utility of the thin film catalyst in the Suzuki鈥揗iyaura reaction with several substrates as well as in the Heck and Sonogashira coupling reactions is carried out.