Coordination Polymers As Catalysts in Knoevenagel Condensations─A Critical Review Analysis under Synthesis Conditions and Green Chemistry
Luca Dias Tavares Louzada, Pedro N. Batalha, Filipe B. de Almeida
Abstract
High Resolution Image Download MS PowerPoint Slide Knoevenagel condensation is an important reaction where C–C double bonds can be formed by reacting carbonyl with active methylene compounds. For materials and pharmaceutical chemistry, this reaction plays an important role in the search for new products for which an effective catalyst is fundamental. Due to its high activity, selectivity, and facile recovery, coordination polymers stand as an important heterogeneous catalyst for Knoevenagel condensation. This review builds an extensive analysis correlation between synthesis conditions and coordination polymer properties as catalysts. The pivotal correlation between solvent properties (protic/aprotic), reaction conditions, and the influence of coordination polymer dimensionality on the reaction selectivity is thoroughly examined. The mono/bifunctional catalyst characteristic is also highlighted, with an in-depth examination of the reaction mechanism to clarify the contribution of Lewis acid and basic sites. Further, the reaction under environmentally friendly conditions was identified among all of the reactions to determine the greenest catalyst. In this perspective, this perspective establishes a robust foundation for the future design and application of coordination polymers as catalysts in Knoevenagel condensation.