酸性沸石分子筛催化Knoevenagel缩合反应  

Knoevenagel Condensation over Acidic Zeolite

作　　者：左伯军[1] 王琪珑[1] 王远[2] 马玉道[1] 

机构地区：[1]山东大学化学系,山东济南250100 [2]北京大学物理化学研究所,北京100871

出　　处：《催化学报》2002年第6期555-558,共4页

摘　　要：在高硅 /铝比的酸性沸石分子筛HY上实现了Knoevenagel缩合反应 .Br nsted酸和Lewis酸均可催化Knoevenagel缩合反应 .考察了羰基化合物和活泼亚甲基化合物的反应活性顺序 .结果表明 ,羰基化合物的羰基极化程度越高 ,反应越容易进行 ;不同于碱催化时的Knoevenagel缩合反应 ,活泼亚甲基化合物的活泼氢的酸性并不是影响其反应活性的重要因素 .Knoevenagel condensation of carbonyl substrates with the compounds containing active methylene group to olefin and water was performed successfully over acidic zeolite HY, and a series of α,β unsaturated compounds were synthesized in satisfactory yield. The factors influencing the reaction were tentatively studied. Both Lewis acid and Brnsted acid are capable of catalyzing the Knoevenagel condensation. And the Brnsted acid strongly promotes the hydrolysis of the condensation products. It was found that aldehydes are more active than ketones, as to aromatic aldehydes, the unsubstitued aromatic aldehydes are more active than those substituted by electron donating groups when undergoing Knoevenagel condensation, but less active than those substituted by electron attracting groups. In other words, the more highly the carbonyl group of the substrate is polarized, the more rapidly the substrate undergoes the Knoevenagel condensation. This conclusion is just the same as that obtained under other conditions. For a given aldehyde or ketone, the reactivity order of active methylene compounds is as follows: ethyl acetoacetate≈cyanoacetamide>acetoacetone>methyl malonate≈ethyl malonate>malononitrile>ethyl cyanoacetate. It differs greatly from the activity order of the active hydrogen of the active methylene compounds, meaning that the acidity of the active hydrogen contained in the reactants is not the principal factor influencing the reaction rate of the condensation.

关 键 词：酸性沸石分子筛 醛 酮 亚甲基化合物 KNOEVENAGEL缩合反应 羰基化合物 催化剂 

分 类 号：O643.3[理学—物理化学]