Palladium‐Iminodiacetic Acid Immobilized on pH‐Responsive Polymeric Microspheres: Efficient Quasi‐Homogeneous Catalyst for Suzuki and Heck Reactions in Aqueous Solution
2008; Wiley; Volume: 350; Issue: 13 Linguagem: Inglês
10.1002/adsc.200800304
ISSN1615-4169
AutoresJianzheng Zhang, Wangqing Zhang, Yao Wang, Minchao Zhang,
Tópico(s)Organoboron and organosilicon chemistry
ResumoAbstract The pH‐responsive core‐shell microspheres of poly(styrene‐ co ‐methylacrylic acid) (PS‐ co ‐PMAA) containing a polystyrene (PS) core and a poly(methylacrylic acid) (PMAA) shell are synthesized by one‐stage soap‐free copolymerization and the catalyst system palladium‐iminodiacetic acid (IDA‐Pd) is immobilized on the outer shell‐layer of the core‐shell microspheres to form the quasi‐homogeneous and easily accessible catalyst PS‐ co ‐PMAA‐IDA‐Pd. This quasi‐homogeneous PS‐ co ‐PMAA‐IDA‐Pd catalyst is highly dispersed in the reaction medium just like a homogeneous one and can be separated like a heterogeneous catalyst by adjusting the pH of the reaction medium. Suzuki reactions employing the quasi‐homogeneous PS‐ co ‐PMAA‐IDA‐Pd catalyst are efficiently performed in water as the sole solvent under mild conditions such as room temperature. The PS‐ co ‐PMAA‐IDA‐Pd catalyst is also used in Heck reactions of a wide range of aryl halides with styrene and proves to be efficient in aqueous solution. The PS‐ co ‐PMAA‐IDA‐Pd catalyst has a low leaching loss and can be reused at least 4 times without loss of activity.
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