Poly(vinylidene dichloride)-diethylene Triamine Supported Palladium as a New Re-cyclable Catalyst for Heck Reaction

Poly(vinylidene dichloride)-diethylene triamine supported palladium complex (PVDC-DTA-Pd) was prepared from poly(vinylidene dichloride) by a simple method. In contrast with other polymer-supported catalysts, the greatest advantage of the catalyst system was that the cost of the catalyst was remarkably low due to the easily obtained materials and the simple synthetic route. Heck reactions of aryl iodides with acrylic acid catalyzed by PVDC-DTA-Pd could be performed efficiently in water. Yield of cinnamic acid was 99.6% as the coupling of iodobenzene with acrylic acid was carried out in water at 90°C for 3 h in the air. Both electron-rich and electron-deficient aryl iodides reacted with the alkenes to give the corresponding trans-products. When styrene was adopted as alkene, high yields were obtained in DMF rather than in water because the hydrophilicity of styrene was poor. High activities for aryl bromides and activated aryl chlorides were also found when the reactions were carried out in tetrabutylammonium bromide to afford the coupled products in moderate to good yields. However, high temperature (120°C) and inert atmosphere were required. The catalyst can be recovered easily by filtration and re-used for Heck reaction. Yield of the cinnamic acid was up to 78.5% at the cycle of five, which indicated the high stability and good re-usability of PVDC-DTA-Pd.