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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.[a] A.

The present work focused on developing a new protocol of the 1-(benzothiazolylamino) methyl-2-naphthol derivatives synthesis by condensation of three compounds, i.e. aromatic 2-naphthol, 2-aminobenzothiazole and aldehyde. Furthermore, this reaction was carried out in the presence of three heterogeneous phosphate catalysts: monoammonium phosphates (MAP), diammonium phosphate (DAP), and trisuperphosphate (TSP). Moreover, this method offered many advantages, such as: very high yields, shorter reaction times, and the catalysts, can be easily recovered and reused without any loss of their catalytic activities.  Copyright ©2019 BCREC Group. All rights reserved

The novelty of this work is to propose a new process consisting to the modification of triple superphosphate (TSP) by sodium nitrate (NaNO3) for the preparation of a heterogeneous catalytic support Na2Ca(HPO4)2 (calcium hydrogen disodium phosphate). This product has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR). The catalytic activity of Na2Ca(HPO4)2 was examined in Knoevenagel condensation between 4-chlorobenzaldehyde and malononit rile as a model reaction. The optimization of the reaction operating conditions was carried out based on a study of the effect of various parameters, namely reaction time, the catalyst charge, the nature, and volume of solvent on the reaction yield. From these considerations, this catalyst proves its efficiency since it allows to obtain the product with excellent yields in a short reaction time. Moreover, it has been reused several times without any significant loss of its activity. The process developed herein can be considered as an ecological and economical method because the catalyst used is non-toxic, cost-effective and easy to prepare.