Valorization of the Modified Mono Ammonium Phosphate by Cobalt in the Synthesise of 3,4‐Dihydropyrano[c]chromene Derivatives

Abstract

Abstract This work presents a simple process for the preparation of Cobalt Orthophosphate (Co 3 (PO 4 ) 2 ), by modifying phosphate fertilizer mono‐ammonium phosphate (MAP) by cobalt nitrate (Co(NO 3 ) 2 ). Co 3 (PO 4 ) 2 has been characterised using microscopic and spectroscopic methods namely X‐ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). It is the first time that Co 3 (PO 4 ) 2 is used as a heterogeneous catalyst in the condensation between an aryl aldehyde, 4‐hydroxycoumarin and malononitrile. The results show that Co 3 (PO 4 ) 2 is an effective catalyst for one‐pot synthesis of 3,4‐dihydropyrano [3, 2‐c] chromene. The optimisation of each reaction parameter allows achieving excellent results in terms of time and yield. The application of Co 3 (PO 4 ) 2 as catalyst in the 3, 4‐dihydropyrano [3, 2‐c] chromene derivatives synthesis offers certain advantages such as shorter reaction time, simple treatment, furthermore, the catalyst possesses a great capacity for reutilization and therefore its application contributes to the development of green chemistry.