Amine-Functionalized Graphitic Carbon Nitride as a Sustainable Metal-free Catalyst for Knoevenagel Condensation

Design and development of sustainable metal-free heterogeneous catalysts for organic transformation reactions is a challenging task. In this work, an amine-functionalized graphitic carbon nitride (NH2-GCN) was prepared and used as a heterogeneous solid base catalyst for Knoevenagel condensation reaction. The amine functionalization led to increased basicity due to the presence of additional -NH2 groups. The catalytic potential of NH2-GCN was tested for Knoevenagel condensation, which showed good catalytic activity. The detailed optimizations of various reaction conditions, such as time, temperature, solvent, and catalyst amount, were performed. The catalyst showed the highest yield of 92% with excellent selectivity, wherein only a single product was formed. Furthermore, the wide applicability was investigated by studying the substrate scope, and a high turnover number was obtained with almost all the substrates. In addition, green metrics parameters were also determined, and the stability and recyclability of the catalyst were also studied. Overall, the work provides a green, sustainable, and metal-free approach for Knoevenagel condensation reaction.