Ba(OH) 2 as the catalyst in organic reactions : XI. Halide-Promoted Activated Barium Hydroxides

The effects of halide ions on the surface properties of an activated barium hydroxide catalyst are described. KF, KCl, KBr, and KI were used as activating salts. KF destroys the catalyst under experimental conditions, giving BaF 2. The halide-promoted catalysts have Ba(OH) 2 · 8H 2O as their support, with crystals of anhydrous KCl, KBr, or KI on their surface. The most active halide-promoted catalysts are more basic than the activated barium hydroxide and Ba(OH) 2 · 8H 2O catalysts. They are more active as catalysts than the barium hydroxide catalysts when the Michael addition of diethyl malonate to chalcone is used as a reaction test.