Coconut endocarp shell ash (CESA): a non-conventional catalyst for green synthesis of 2- amino-4H-benzochromenes

In the present research, the coconut endocarp shell as a natural waste was converted into a valuable non-conventional catalyst by simple thermal treatment, namely coconut endocarp shell ash (CESA). The prepared CESA was characterized using several analytical techniques, including TGA, FT-IR, XRD, BET, SEM, and EDX. The catalytic property of the CESA was examined in the synthesis of pharmaceutically active 2-amino-4 H -benzochromene derivatives via one-pot three component condensation of aldehydes, malononitrile, and α or β-naphthol in ethanol at room temperature. The most promising aspects of the presented approach are the high catalytic efficiency, short reaction time, excellent yield of products, operational simplicity, waste to wealth, and optimization with the design of experiment. Moreover, the CESA catalyst was recycled five times without any apparent loss of its catalytic activity.