纳米稀土复合固体超强酸催化合成胡萝卜酸乙酯

目的 研究纳米稀土复合固体超强酸催化剂对合成胡萝卜酸乙酯的影响,确定最佳反应条件.方法 稀土复合固体超强酸SO42/ZrO2-2％Nd2O3催化剂利用化学共沉淀法制备,并用电镜分析方法研究其相关性质;采用正交试验来确定胡萝卜酸乙酯催化合成的最佳条件.同时利用折光率、元素分析、气相色谱、红外光谱等对产品进行物性、组成和结构表征.结果 电镜分析表明,自制催化剂颗粒直径在15 nm左右,比表面积达200.56 m2/g,酸强度为-12.70＜H0＜-11.99.通过正交实验确定的酯化反应优化条件是：n乙醇∶n丙二酸为3.0∶1.0,催化剂用量为反应物总质量的2.0％,反应时间为120min,反应温度为95～105℃,带水剂环己烷用量为20 mL,酯化率可达97％以上.各种分析结果一致表明,催化合成所得之物与胡萝卜酸乙酯标准相符合.结论 该催化剂具有良好的催化活性和重复使用性,反应条件温和,方法简便,酯化率高,具有很强的实用价值.

Synthesis of diethyl malonate catalyzed by nanometer rare earth composite solid superacid

Objective--To study the effects of nanometer rare earth composite solid superacid on the catalytic synthesis reaction of diethyl malonate and to confirm the optimal conditions. Methods-- Rare earth composite solid superacid SO24-/ZrO2-2 %Nd2O3 was prepared with co-precipitation method and its properties were studied by electron microscope analysis. The optimum conditions of the catalytic synthesis reaction of diethyl malonate were determined through orthogonal experiments. Meanwhile, the property, composition and structure of the products were characterized by refractive index, elemental apalysis, GC and IR. Results --The analysis results of TEM showed that the average particle size of self-synthetical catalyst was about 15 nm. Its specific surface area was 200.56 m2/g, and its acidity （H0） was between --12.70 and --11.99. The optimum reaction conditions of the esterification obtained with orthogonal experiments were as follows： the molar ratio of ethanol to malonic acid is 3.0：1.0, the use level of 5024-/ZrO2-2%Nd2O3 catalyst was 2.0% of the total mass of the reactants; the reaction time was 120 min, the reaction temperature was 95-105℃, the dosage of cyclohexane used as water-carrying agent is 20 mL and the esterification conversion was more than 97%. All analysis results showed that the catalyzed synthesis product was consistent with the diethyl malonate standard. Conclusion--The catalyst has excellently catalytic activity and good reusability. This method has advantages of mild, convenient, high esterification yield and extensive utilization.