Revisiting the Knoevenagel condensations: A universal and flexible bis-ammoniated fiber catalyst for the mild synthesis of α,β-unsaturated compounds

Abstract

Abstract A universal fiber catalyst for the Knoevenagel condensations is presented. The detailed characterization by mechanical properties, elemental analysis, FTIR spectroscopy, and SEM confirmed the rangeability of the fiber catalyst during the full-course. Moreover, the mediated condensations proceeded smoothly with lower catalyst amount (1 mol%) in different solvents of varying polarities and the products were obtained in good to excellent yields (95–99%), and even with water as the solvent could also achieve a series of α,β-unsaturated compounds with nearly quantitative yields at room temperature. Furthermore, the catalyst exhibited excellent flexibility and could be easily recovered and recycled with prominent stability over 10 cycles, and the procedure was operationally convenient and effectively amenable to the gram scale on a simple fixed-bed reactor.