Polystyrene microsphere-immobilized palladium(II) porphyrin as mild, reusable, and highly efficient catalyst for Heck reaction

• A palladium(II) porphyrin complex was successfully immobilized on PMs surfaces.
• The Pd-MTP/PMs catalyst gave higher GC yield in Heck reaction of iodobenzene with ethyl acrylate.
• The catalyst showed better reusability with no Pd leaching in the Heck reaction.

A novel Heck reaction catalyst consisting of a palladium(II) complex of meso-tetra(p-hydroxyphenyl)porphyrin (MTP) and cross-linked chloromethylated polystyrene microspheres (PMs) was successfully prepared via covalent ether bonds between the chloride groups in the PMs and the hydroxyl groups in MTP. The catalyst was characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). This polystyrene-supported palladium-complex was an efficient heterogeneous catalyst for cross-coupling of aryl iodides with ethyl acrylate. The reaction of iodobenzene and ethyl acrylate under N2 at 100 °C and a catalyst concentration of 0.1% gave a gas chromatography product yield of 99.8%, which is much higher than that achieved using a free palladium(II) complex of MTP as the catalyst (41.3%). The catalyst was recycled up to six times without significant loss of catalytic activity. These results suggest that the immobilized palladium(II)–MTP catalyst has potential applications in synthetic and industrial chemistry.

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