عنوان مقاله [English]
The maim elements of chromite ore were deduced by X-ray fluorescence (XRF) after collection and grinding. The presence of irregular designs in the form of cavities with size of 50 to 200 micrometers and sometimes nanometers in the structure of this catalyst using solid surface morphology with SEM and TEM electron micrograph scanning was confirmed. In a one-pot three component reaction of diver's aromatic aldehydes, barbituric acid and urea or thiourea, pyrimidopyrimidine (5 , 6 –dihydro – 5 – aryl pyrimido [4 , 5 - d] pyrimidine – 2 , 4 , 7 (1H , 3H , 8H ) - trione) heterocyclic products were prepared in the presence of chromite ore as natural catalyst. There was no need for the column purification of the products in these reactions. Moreover, this methodology offered several advantages such as good yields, simple procedure and simple purification steps. Using water as solvent made the process environmentally and economically benign.