Studies On Synthesis Of Vanadium Iron Substituted Dawson-type Polyoxometalates And Their Catalysis In Epoxy Organic Reaction

This paper synthesized six types of Dawson-type polyoxometalates containing different number of V and Fe atoms started from Dawson-type polyoxometalates, and prepared a new type of their corresponding quaternary ammonium salts. Their Dawson-type structure was characterized by IR,UV,elementary analysis and TG. Therefor their formula were deduced: K₉P₂W₁₇FeO₆₂·16H₂O K₉P₂W₁₆VFeO₆₂·15H₂O K₉P₂W₁₅V₂FeO₆₂·15H₂O K₉P₂W₁₄V₃FeO₆₂·15H₂O K₉P₂W₁₃V₄FeO₆₂·15H₂O K₉P₂W₁₂V₅FeO₆₂·15H₂O [(C₄H₉)₄N]₉P₂W₁₃V₄FeO₆₂·6H₂O The most highly oxidation value of the addenda atoms was showed in the polyoxometalates, so they had comparatively oxidative catalysis. At the same time, polyoxometalates were solid high acidity, they were redox and acidity difuction catalysts. Polyoxometalates had pole structure, so they showed high catalytic activity and special selectivity in organic reaction in homogeneous as well as heterogeneous systems. In this paper, twelve types of Dawson-type polyoxometalates were studied as catalysis in epoxy reaction of maleic acid, and studied the conditions of the oxidal reaction. From the experimentation, different polyoxometalates had different catalyst activity could be concluded, the more V atoms in the catalyst, the stronger catalyst activity, and the catalysis of the quaternary ammonium salts were stronger than potassium salts, and the pH of the solution should be considered, if the pH was in the range of 4.0-5.0, the catalysis had no remarkable change, and if it was out of the range, the yield was less than 30%.