Study On Preparation Of Vanadium Cobalt Substituted Dawson-type Polyoxometalates And Their Catalysis Activities In Pharmaceuticals Organic Synthesis Reaction

This paper synthesized four kinds of Dawson-type polyoxometalates containing different number of vanadium and cobalt atoms started from Dawson-type polyoxometalates. Their Dawson-type structure was characterized by IR,UV,elementary analysis and TG. . Therefore their formulae were deduced: K₉P₂W₁₇CoO₆₂·16H₂O K₁₀P₂W₁₆CoVO₆₂·15H₂O K₁₁P₂W₁₅CoV₂O₆₂·15H₂O K₁₂P₂W₁₄CoV₃O₆₂·15H₂OPolyoxometalates were solid strong acidity, and they were redox and acidity difunctional catalysts. Polyoxometalates had pole and cage structure, so they showed high catalytic activity and special stereoselectivity in organic reaction in homogeneous as well as heterogeneous systems.In this paper, four kinds of Dawson-type polyoxometalates were studied as catalysis in acetal or ketal reaction of 16α-hydroxyprednisolone reaction with cyclohexanealdehyde and acetone, and studied the conditions of the acetal or ketal reaction. From the experimentation, that different polyoxometalates had different catalyst activity could be concluded, the more V atoms the catalyst had, the stronger oxidative activity the catalyst had, and it's acidity catalysis activity became mild. This was just acidity catalysis activity needed in my papers. Only under acidity conditions, the experimentation proved that the catalyst showed strong catalytic activity and particular stereochemistry selectivity.