Water extract of incense stick ash: an efficient, greener approach for the synthesis of 2-pyridones via multi-component reaction approach

An eco-benign, efficient, cost-effective, high energy-efficient method has been devised for synthesizing diamino-4-phenyl-3,5-dicyano-2-pyridone through a one-pot, three-component reaction. The technique involves the reaction of aryl aldehyde, malononitrile, and cyanoacetic acid hydrazide at 60 °C, utilizing water extract of incense stick ash as a catalyst and recyclable medium. Utilizing water extract as a solvent and catalyst reduces dependency on hazardous and harmful solvents, which are typically non-renewable and contribute to unfavorable emissions. The used incense stick ash was characterized by XRD and EDS analysis. The ash extract consists of metal oxides and carbonates which are basic and can act as catalysts. The reaction proceeds through the Knoevengel reaction, subsequent Michael addition and followed by intramolecular cyclization to furnish N-amino-2-pyridone in good to excellent yields. The structures of the synthesized compounds were confirmed based on IR, ¹H, and ¹³C NMR spectral data analysis.

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