Palladium-Iminodiacetic Acid Immobilized on pH-Responsive Polymeric Microspheres: Efficient Quasi-Homogeneous Catalyst for Suzuki and Heck Reactions in Aqueous Solution

Authors

  • Jianzheng Zhang,

    1. Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin, 300071, People's Republic of China, Fax: (+86)-22-2350-3510, phone; (+86)-22-2350-9794
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  • Wangqing Zhang,

    1. Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin, 300071, People's Republic of China, Fax: (+86)-22-2350-3510, phone; (+86)-22-2350-9794
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  • Yao Wang,

    1. Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin, 300071, People's Republic of China, Fax: (+86)-22-2350-3510, phone; (+86)-22-2350-9794
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  • Minchao Zhang

    1. Key Laboratory of Functional Polymer Materials of Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin, 300071, People's Republic of China, Fax: (+86)-22-2350-3510, phone; (+86)-22-2350-9794
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Abstract

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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