Study On Aldehyde And Acetic Anhydride Reaction Over Keggin Type Molybdovanadophosphoric POMs Catalyst

Polyoxometalates(abbreviated as POMs), especially POMs containing vanadium, have been investigated extensively in catalytic field for their high catalytic performance and selectivity, moderate reaction conditions,non-corrosion, especially for their redox and acidic properties can be controlled at atomic or molecular levels by changing the chemical composition. the double-functional property of acidity and redox, and the pseudoliquid-phase characteristic. Therefor, it has important research and industrial significance to develop their applied research in organic synthesis and catalytic field.Based on the investigation of literatures, this dissertation was focused on the research of some organic relactions catalyzed by molybdovanado- phosphoric POMs catalytic systems. The main progress and research results have been obtained as follows:1. Study on aldehyde and acetic anhydride reaction over Keggin Type Molybdovanadophosphoric POMs Catalyst( M_xPW₁₂O₄₀·nH₂O and M_xPMo₁₂O₄₀·nH₂O)A series of Keggin-type Molybdovanadophosphoric POMs were synthesized and the characterization with IR, X-ray confirmed the formation of the Keggin structure of these compounds. Among the tested catalysts. FePW₁₂O₄₀ is the best one, including addition amount, reaction time, molar ratio of Aldehyde and Acetic Anhydride , And speculated on possible reaction mechanism and activity center, obtained the following basic conclusionKeggin-type Molybdovanadophosphoric POMs FePW₁₂O₄₀ was used for the first time as a catalyst in the acetal formation, and found to be good catalytic system for this transformation. The suitable reaction conditions are FePW₁₂O₄₀ catalyst amount, 0.034 mmol; reaction time 5 min, molar ratio of Aldehyde and Acetic Anhydride=1:3,at room temperature under solvent-free and 59.19-94.85% yield of the corresponding 1,1-diacetates could be obtained. The experimental procedure is quite simple and convenient, and the reaction conditions are amenable to scale-up. 2.Study on aldehyde and acetic anhydride reaction over Keggin Type Molybdovanadophosphoric POMs Catalyst LnPW₁₂O₄₀·nH₂O (L n = L a,Ce,N d,Sm)A series of Keggin-type Molybdovanadophosphoric POMs were synthesized and the characterization with IR, X-ray confirmed the formation of the Keggin structure of these compounds. Among the tested catalysts. NdPW12O40 is the best one, including addition amount, reaction time, molar ratio of Aldehyde and Acetic Anhydride , And speculated on possible reaction mechanism and activity center, obtained the following basic conclusionKeggin-type Molybdovanadophosphoric POMs NdPW12O40 was used for the first time as a catalyst in the acetal formation, and found to be good catalytic system for this transformation. The suitable reaction conditions are NdPW12O40 catalyst amount, 0.1 g; reaction time 5 min, molar ratio of Aldehyde and Acetic Anhydride=1:3,at room temperature under solvent-free and 56-98.3% yield of the corresponding 1,1-diacetates could be obtained. 3.An ew environmental friendly catalyst,LaPMO12O40/SiO₂ was prepared. The FT-IR and X-ray spectroscopy indicated that the structure of catalysts were Keggin type. Experimental results showed that a series of aldehydes and acetic anhydride can reacts, corresponding 1,1-diacetates at room temperature under solvent-free conditions by using heteropoly acid catalys as catalyst, Under the optimum conditionsLaPMO12O40/SiO2.catalys amount 0.1 g, molar ratio of Aldehyde and Acetic Anhydride=1 : 3, and 60.2⁹0.5 % yield of the corresponding 1,1-diacetates could be obtained.