Palladium catalysts supported on amine-functionalized glycidyl methacrylate gel type terpolymers. Synthesis, characteristics and study of catalytic activity in Suzuki–Miyaura reactions

• Novel recyclable Pd catalysts for Suzuki–Miyaura reactions under mild conditions.
• Amino functionalized methacrylate–styrene gels as supports for Pd catalysts.
• Amine unit structure and Pd(II) ion loading as factors determining catalyst activity.
• ArBr/KOH ratio as a factor determining catalyst stability and activity.

A series of amine functionalized resins (1–7) with ethylenediamine (EDA), N,N-dimethylethylenediamine (DMEDA), N,N-diisopropylethylenediamine (DIPEDA), 2-methoxyethylamine (MEOEA), diethylenetriamine (DETA), tris(2-aminoethyl)amine (TAEA), triethylenetetramine (TETA) functionalities were prepared by chemical modification of the terpolymer of glycidyl methacrylate (20 mol%), styrene (77 mol%) and divinylbenzene (3 mol%). The resins obtained in this way were used for preparation of two series of polymer supported palladium catalysts consisting of about 3.6 wt% of Pd(II) ions (N/Pd > 2) and maximal possible loadings of Pd(II) ions (8.0–15.9 wt% Pd, N/Pd < 2). The catalysts were characterized using FT-IR, DR UV–Vis, HR-SEM and ICP-OES methods. Catalytic studies of the cross-coupling reaction of bromobenzene and phenylboronic acid in a medium of the i-PrOH/H2O solvent system with KOH as a base were also performed. The effect of catalyst and KOH concentrations, the nature of amine units and aryl bromides and reaction temperature was studied. The most active catalyst could be used minimum five times to perform the coupling of bromobenzene and phenylboronic acid efficiently. However, the lowering of the catalyst activity was observed after each cycle.

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