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合成了一系列Brnsted酸性离子液体并将其应用在醛醇缩合反应中.醛醇缩合产物由于极好的溶剂性质等被广泛用作溶剂和试剂.离子液体[BSmim][OTf]在甲醛和乙二醇缩合生成1,3-二氧五环的反应中表现出了极好的催化活性,甲醛转化率和主产物1,3-二氧五环选择性分别可以达到96.1%和92.4%.对影响离子液体催化性能的因素进行了探索,并对催化反应中的离子液体的用量、反应温度、反应时间以及反应物料比进行了考察.通过Hammett酸度函数法测定了所用到离子液体的酸性,结果表明离子液体酸性与其在缩合反应中的催化活性顺序完全一致,酸性越强催化性能越好.结合实验给出了离子液体[BSmim][OTf]催化甲醛和乙二醇缩合反应的可能的反应机理.该催化剂体系具有良好的催化性能,反应可以在较温和的条件下进行,实现了高活性和高选择性的目标,产物易分离,催化剂重复使用7次,其催化活性基本不变.并将该Brnsted酸性离子液体进一步应用到其他醛(酮)醇缩合反应中.
A series of Brönsted acidic ionic liquids were synthesized and used in the aldol reaction.The aldol condensation products are widely used as solvents and reagents due to their excellent solvent properties etc. [BSmim] [OTf] And ethylene glycol to 1,3-dioxolane showed excellent catalytic activity, formaldehyde conversion and the main product of 1,3-dioxane selectivity of 96.1% and 92.4%, respectively, The factors affecting the catalytic performance of ionic liquids were explored, and the amount of ionic liquids, reaction temperature, reaction time and the ratio of reactants in the catalytic reaction were investigated.The acidity of ionic liquids used was determined by Hammett acidity function method The results showed that the ionic liquid had the same acidity as the order of its catalytic activity in the condensation reaction, and the stronger the acidity, the better the catalytic performance.The ionic liquid [BSmim] [OTf] was proposed to catalyze the condensation of formaldehyde and ethylene glycol Reaction mechanism.The catalyst system has good catalytic performance, the reaction can be carried out under milder conditions, to achieve high activity and high selectivity of the target, the product is easy to separate, the catalyst reused 7 times, its catalytic activity is basically unchanged, and the Brnsted acidic ionic liquid is further applied to other aldehyde (ketone) alcohol condensation reaction.