Polystyrene-supported ammonium fluoride as a catalyst for several base-catalyzed reactions

Noritaka Ohtani, Yukihiko Inoue, Akira Nomoto, Shigeyuki Ohta
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引用次数: 7

Abstract

Lightly crosslinked polystyrenes with ammonium chlorides were ion-exchanged to a fluoride form. The fluoride polymers functioned as good catalysts for several base-catalyzed reactions, such as cyanoethylation, Knoevenagel reaction, Claisen condensation and Michael addition. Their catalytic activity was comparable to that of tetrabutylammonium fluoride (TBAF). The factors controlling the catalytic efficiency for the reaction between ethyl acetoacetate and benzaldehyde were examined in detail. Ionic loading and ammonio structure of the fluoride polymers hardly affected the catalytic efficiency. The reaction was fast in a non-polar solvent, such as octane or toluene. The solvent effect was very similar to that of nucleophilic substitution reactions. These results suggest that the rate-determining step of the base-catalyzed reaction is not the formation of a conjugate base from the reagent acid, but the attack of the nucleophilic anion on electrophiles.

聚苯乙烯负载氟化铵作为几种碱催化反应的催化剂
轻交联聚苯乙烯与氯化铵离子交换成氟化物形式。氟聚合物对氰基化反应、Knoevenagel反应、Claisen缩合反应和Michael加成反应等碱催化反应具有良好的催化作用。它们的催化活性与四丁基氟化铵(TBAF)相当。详细考察了影响乙酰乙酸乙酯与苯甲醛反应催化效率的因素。氟化聚合物的离子负载和氨结构对催化效率影响不大。在非极性溶剂中,如辛烷或甲苯,反应很快。溶剂效应与亲核取代反应非常相似。这些结果表明,碱催化反应的速率决定步骤不是由试剂酸形成共轭碱,而是亲核阴离子对亲电试剂的攻击。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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