Molybdenum carbide as an efficient and durable catalyst for aqueous Knoevenagel condensation†
By following green chemistry principles, various molybdenum compounds as cost-effective, commercially available, heterogeneous, and benign catalysts were used for the Knoevenagel condensation reaction. Among the compounds (Mo2C, MoS2, MoB, MoSi2), molybdenum carbide showed efficient performance for the Knoevenagel condensation in aqueous media at room temperature, affording the corresponding products in high yields within a short reaction time. Notably, using this commercially available heterogeneous catalyst, the deacetalization-Knoevenagel condensation of benzaldehyde dimethyl acetal and malononitrile at room temperature could successfully proceed in excellent yield. Molybdenum carbide could be recovered five times without loss of activity with an operationally simple procedure.