Eco-friendly grinding synthesis of a double-layered nanomaterial and the correlation between its basicity, calcination and catalytic activity in the green synthesis of novel fused pyrimidines

The synthesis of hydrotalcite using Al : Mg molar ratios of 1.0 : 3.0 by a grinding method at room temperature is reported. The prepared hydrotalcite was characterized by TG, FT-IR, SEM, XRD and Hammett titration method. The calcined hydrotalcite with a Mg : Al molar ratio of 3 : 1 derived from calcinations at 750 K was found to be a suitable catalyst that can give the highest basicity and the best catalytic activity for this synthesis. The effect of the molar ratio, catalyst loading, reaction time and basicity was investigated in the facile, efficient and green synthesis of novel fused pyrimidines by a three-component reaction of 4-hydroxy coumarin, aldehydes and 2-amino benzothiazole under solvent-free conditions for the first time. The influence of the hydrotalcite and the different amounts of it on reactivity was studied. It was found that the best yield was obtained with 80 mg of catalyst loading in the least time as compared to the other catalysts used. This protocol reported herein represents a rapid and cost-effective route for the synthesis of hydrotalcites and reports on their versatile applications for the synthesis of densely functionalized novel fused pyrimidines.