A highly efficient and green method for catalyzing the Hantzsch reaction under solvent-free conditions using a seashell/Kaolin calcined system

• Published in: Journal of chemical sciences (Bangalore, India) India), 2023-07, Vol.135 (3), Article 70
• Main Authors: Stiti, Mohamed-Zakaria, Habila, Tahir, Khaled, Ammar, Bouhedja, Mourad, Pireaux, Jean-Jacques, Khelili, Smail
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Regular Article
• ISSN: 0973-7103; 0973-7103
• DOI: 10.1007/s12039-023-02190-1

A green method for synthesizing 1,4-dihydropyridines ( 1a-j ) by a one-pot reaction of various aldehydes, ethyl acetoacetate, and ammonium carbonate, catalyzed by a seashell and kaolin powders, mixed and calcined at 500 and 800 °C, under solvent-free conditions, has been developed. The catalyst was characterized by physicochemical techniques, namely, X-ray diffraction (XRD), electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The mixture composed of 20% seashell and 80% Kaolin (Q3-500), calcined at 500 °C, gave the best results (78 to 96% yields). Q3-500 separation from the reacting medium was carried out by filtration and reused several times with a slight decrease in yields. Compared with other conventional methods, the present method is inexpensive and offers advantages, namely: the catalyst is eco-friendly, recyclable, and gives high yields with shorter reaction time. Graphical Abstract A seashell/Kaolin calcined system (20/80) at 500°C was elaborated to catalyze the Hantzsch reaction under solvent-free conditions. Using Q3-500 six times gave dihydropyridines with excellent yields with a slight loss of activity. The improvement of the catalytic properties of the kaolin surface is due to the increase of cationic content.