KF-γ-Al_2O_3催化正丁醛自缩合合成辛烯醛

Aldol Self-Condensation of n-Butyraldehyde to 2-Ethyl-2-Hexenal Catalyzed by KF-γ-Al_2O_3

催化正丁醛自缩合生成辛烯醛的反应是工业上生产有机化工原料辛醇(2-乙基己醇)的重要反应。笔者对该反应所需的酸碱双功能催化剂进行筛选,然后采用筛选出的催化剂,考察了反应条件对正丁醛自缩合反应的影响。结果表明,该反应适宜的酸碱双功能催化剂为KF与γ-Al_2O_3质量比为9.0的KF-γ-Al_2O_3。最佳的反应条件为KF-γ-Al_2O_3与正丁醛质量比0.10、反应温度为120℃、反应时间为6h,此时,正丁醛的转化率为99.0%,辛烯醛的收率和选择性分别为98.1%和99.1%。KF和γ-Al_2O_3的协同催化作用促进了KF-γ-Al_2O_3催化体系对正丁醛自缩合反应催化性能的提高。在此基础上,推测了KF-γ-Al_2O_3催化正丁醛自缩合反应的酸碱协同作用机理。

Catalytic aldol self-condensation of n-butyraldehyde to produce 2-ethyl-2-hexenal is one of the reactions for industrial production of the important organic chemicals, 2-ethylhexanol. The catalytic performances of a series of potassium salt-solid acid catalysts for the self-condensation were evaluated, and then with the optimal potassium salt-solid acid catalyst the effects of reaction conditions on the catalytic reaction were investigated to get the suitable reaction conditions. The results showed thatKF-γ-Al2O3 with KF-γ-Al2O3 mass ratio of 9.0 possessed the best catalytic activity among the tested catalysts. The suitable conditions for catalytic aldol self-condensation of n-butyraldehyde were KF-γ-Al2O3 to n-butyraldehyde mass ratio of 0.10, reaction temperature of 120℃ and reaction time of 6 h, under which the conversion of n-butyraldehyde reached 99.0%, the yield and selectivity of 2-ethyl-2-hexenal were 98.1% and 99.1%, respectively. The synergistic effect of KF and KF-γ-Al2O33 may be responsible for the high catalytic performance of KF-γ-Al2O3 Furthermore, the acid-base synergistic catalysis mechanism of KF-γ-Al2O3 was discussed.