An Efficient Polyacrylonitrile Fiber-Based Acid-Base Bifunctional Catalyst for Aqueous One-Pot Cascade Reactions

A novel heterogeneous acid-base bifunctional catalyst was successfully developed by immobilizing primary amine and carboxylic acid groups onto polyacrylonitrile fiber (PANF) through a facile two-step functionalization strategy. This catalyst demonstrated exceptional performance in the one-pot deacetalization-Knoevenagel cascade reaction in water at room temperature. Systematic characterization techniques, including SEM, XRD, FTIR, XPS, and elemental analysis, confirmed the successful integration of dual active sites and structural stability. By optimizing the acid/base ratio, catalyst loading, reaction time, and solvent polarity, the PANF-EC3/2 catalyst achieved a remarkable 97% yield for the cascade reaction of benzaldehyde dimethyl acetal with malononitrile. The catalyst exhibited broad substrate adaptability and outstanding reusability, retaining 86% yield after 10 cycles. A continuous-flow reactor experiment further validated its industrial potential, maintaining 96% yield over 7 days. This work highlights PANF-EC3/2 as a sustainable, cost-effective, and scalable catalyst for green chemical processes.