Calcinized eggshell: an environmentally benign green catalyst for synthesis of 2-arylbenzothiazole derivatives

The calcinized eggshell as an efficient and green catalyst has been prepared from chicken eggshell waste and is characterized by different analytical techniques such as FT-IR, XRD, TGA, SEM, and EDAX. A series of substituted 2-arylbenzothiazoles have been synthesized by reaction of o-aminothiophenol and aromatic aldehydes under solvent free conditions using a grinding method at room temperature. The reaction proceeds smoothly in excellent yields (86–97 %), short reaction time (15–48 min), and with an easy work-up procedure. The reuse of catalyst and purification of products by non-chromatographic methods are some additional features of the present protocol. The calcinized eggshell is a safe, inexpensive, and a green catalyst with high catalytic efficiency obtained from renewable resources.