制备途径对咪唑基酸性聚离子液体催化Prins反应性能影响

The Influence of Preparation Methods on the Catalytic Performance of Imidazole Based Acidic Poly (Ionic Liquids) for Prins Reaction

中文关键词:  酸性聚离子液体  Prins反应  烯烃  三聚甲醛

英文关键词:acidic poly (ionic liquids)  Prins reaction  olefins  paraformaldehyde

中文摘要:

      通过自由基聚合法固载酸性离子液体, 研究了聚合溶剂、聚合顺序、聚离子液体(PILs)酸化时溶剂等对制备咪唑基酸性聚离子液体(APILs)结构的影响, 以芳香烯烃与三聚甲醛的Prins反应考察其催化性能, 并结合多种物理化学表征手段揭示反应的构效关系. 结果表明, 以乙醇为溶剂, 交联剂与乙烯基咪唑鎓盐直接聚合得到的PILs具有更高的热稳定性和硫含量, 这可能是因为溶剂化作用和聚合单体电荷不同导致的. 使用二氯甲烷(DCM)为溶剂酸化PILs得到的酸催化剂具有最高的酸性(5.69 mmol·g^-1), 其能够高效催化苯乙烯与三聚甲醛反应制备4-苯基-1,3-二氧六环. 在温和反应条件下, 苯乙烯转化率为100%, 目标产物选择性达98%, 且催化剂具有良好的循环使用稳定性, 重复使用6次后催化活性未见明显降低. 此外, 该催化剂具有好的底物适用性, 在一系列不同取代芳香烯烃的Prins反应中均表现出优异的性能.

英文摘要:

      The preparation of immobilized acidic ionic liquids through radical polymerization was investigated, focusing on the effects of polymerization solvent, polymerization sequence, and solvent used during the acidification of poly (ionic liquids) (PILs) on the structure of imidazolium-based acidic poly (ionic liquids) (APILs) and their catalytic performance in the Prins reaction of aromatic alkenes with paraformaldehyde. Various physicochemical characterization techniques were employed to reveal the structure-activity relationships. The results indicate that PILs synthesized with ethanol as the solvent and through the direct polymerization of crosslinkers with vinyl imidazolium salts exhibit higher thermal stability and S content, likely due to solvation effects and differences in the charges of the polymerization monomers. The acid catalyst obtained by acidifying PILs with dichloromethane (DCM) shows the highest acidity (5.69 mmol·g^-1), enabling efficient catalysis of the reaction between styrene and paraformaldehyde to produce 4-phenyl-1,3-dioxane. Under mild reaction conditions, the styrene conversion reaches 100%, with a target product selectivity of 98%. Moreover, the catalyst demonstrates good reusability, maintaining its activity after six cycles with no significant decline. Additionally, this catalyst exhibits broad substrate applicability, showing excellent performance in the Prins condensation reactions of various substituted aromatic alkenes.