Reagents and catalysts derived from polybenzimidazole and polystyrene resins with imidazole pendant groups

Poly(benzimidazole) beads and similar reactive polymers containing benzimidazole groups attached to polystyrene resins have been used to prepare a variety of polymer-supported reagents and catalysts. For example, the polymers can be used to prepare supported palladium⁰ catalysts which are effective in the catalytic hydrogenation of nitro compounds or alkenes at room temperature. Poly(benzimidazole) has also been used to prepare a supported regenerable dichromate oxidizing agent. Testing of the reagent under a variety of conditions shows that its effectiveness depends on the percentage of water remaining in the polymer matrix as well as on the temperature used during the preparation of the chromium(VI) complex. However, under certain conditions, poly(benzimidazole) itself is susceptible to oxidative degradation which reduces its usefulness. Sulfonated poly(benzimidazole) is also a useful catalyst in the acetalization of carbonyl compounds. The great thermal stability of poly(benzimidazole) can be used advantageously in other applications such as the gas-phase dehydrohalogenation of trichloroethane to vinylidene chloride.