A green approach to the synthesis of a nano catalyst and the role of basicity, calcination, catalytic activity and aging in the green synthesis of 2-aryl bezimidazoles, benzothiazoles and benzoxazoles

Abstract

A green synthesis of hydrotalcite (a double layered catalyst) by a grinding method using Al/Mg molar ratios of 1.0–3.0 at room temperature is described. The prepared double layered catalyst (hydrotalcite) has been characterized by TG, FT-IR, SEM, XRD and Hammett titration methods. Different factors such as the effect of molar ratios, catalyst loading, reaction time, aging time, and basicity have been investigated for the facile, efficient and green synthesis of 2-arylbenzimidazoles, benzothiazoles and benzoxazoles under solvent free conditions. The influence of catalyst loading on reactivity was studied and a catalyst loading of 20 mg was found to be optimal, giving the best yield with minimum time as compared to other catalysts. The present methodology reports, herein, a rapid and cost effective synthesis of hydrotalcite and its versatile applications in the synthesis of 2-arylbenzimidazoles, benzothiazoles and benzoxazoles.