Application and characterization of eggshell as a new biodegradable and heterogeneous catalyst in green synthesis of 7,8-dihydro-4H-chromen-5(6H)-ones

An efficient and eco-friendly method for the synthesis of 7,8-dihydro-4H-chromen-5(6H)-ones has been developed by using eggshell as a natural and heterogeneous catalyst. A mixture of an appropriate aldehyde, malononitrile and dimedone in the presence of eggshell at ambient temperature in EtOH resulted in 90–98% yields of the corresponding products. This new and green methodology is of interest due to use of a green, bioactive and biodegradable catalyst, its short reaction time, high yields without further purification and the ability to carry out the large scale reactions. Prepared eggshell was characterized by elemental analysis, infrared spectroscopy, particle size distribution, X-ray diffraction and fluorescence, scanning electron microscope, thermo gravimetric and BET surface area analysis.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Eggshell as a new bioactive and heterogeneous catalyst in organic synthesis ► Green, efficient and rapid synthesis of 7,8-dihydro-4H-chromen-5(6H)-ones ► Eggshell characterization with elemental analysis, XRD patterns and FT-IR spectra ► The ability of eggshell to carry out the large scale synthesis ► High catalytic activity and reusability of eggshell even after five cycles