DEVELOPMENT OF SOLID BASE CATALYSTS ACTIVE FOR MICHAEL ADDITIONS AND THEIR RELATED REACTIONS

制备了多种固体碱催化剂，考察了它们对巴豆酸甲酯二聚反应、硝基甲烷与不饱和羰基化合物的加成反应以及醇与丙烯腈的氰乙基化反应的催化性能，以开发对重要的有机合成中形成C-C键的Michael加成反应具有活性的多相催化剂。该反应是通过碱性位点夺取烯丙基质子以形成攻击第二个巴豆酸甲酯的β-位C原子的阴离子中间体而引发的。该反应通过双键迁移作为最后一步完成。MgO的高活性是由于其具有中等的吸附率和高的活性中心密度。对于硝基甲烷与<encircledR>不饱和化合物的Michael加成反应，KF/Al_2O_3和KOH/Al_2O_3表现出高的活性。对反应机理进行了解释，反应物的活性取决于反应物β-碳的电荷密度。对于醇与丙烯腈、碱土金属氢氧化物和氧化物的氰乙基化反应，KF/Al_2O_3、KOH/Al_2O_3和稀土氧化物表现出高的活性。反应速率取决于醇的酸性和活性中心的碱性强度。对于含醇的反应，固体催化剂几乎不受水蒸气和二氧化碳的毒害，这是由于醇与催化剂上碱性中心的强相互作用造成的。

A wide variety of solid base catalysts were prepared, and examined their catalytic properties for dimerization of methyl crotonate, addition of nitromethane to usnsaturated carbonyl compounds, and cyanoethylation of alcohols with acrylonitrile for developing hetergenous catalysts active for Michael addition reactions which are important organic synthesis forming C-C bonds.For dimerization of methyl crotonate, only MgO exhibited a high activity among solid bases examined. The reaction is initiated by abstraction of allylic proton by basic sites to form an anionic intermediate which attacks beta-position C atom of a second methyl crotonate. The reaction completes by double bond migration as a final step. A high activity of MgO is suggested to be due to a moderate absorptivity and high density of active sites.For Michael additions of nitromethane to <encircledR>-unsaturated compounds, KF/alumina and KOH/alumina exhibited a high activity, The reaction mechanisms were elucidated, and the reactivity of reactant depended on the charge denstiy of beta-carbon of the reactantFor cyanoethylation of alcohols with acrylonitrile, alkaline earth hydroxides and oxides, KF/alumina, KOH/alumina, and rare earth oxides exhibited a high activity. The reaction rate are determined by a combination of acidity of alcohol with basic strength of active sites. An alcohol of high acidity reacts faster on a weakly basic catalystFor the reactions involving alcohols, a solid based catalyst is scarcely poisoned by water vapor and carbon dioxide, which is caused by a strong interaction of alcohols with basic sites on the catalysts.